Mixed Race Studies

Self-Reported Race and Genetic Admixture

The New England Journal of Medicine
Number 354, Number 4 (2006-01-26)
pages 431-422
DOI: 10.1056/NEJMc052515

Moumita Sinha, M.Stat.
Case Western Reserve University, Cleveland, Ohio

Emma K. Larkin, M.H.S.
Case Western Reserve University, Cleveland, Ohio

Robert C. Elston, Ph.D.
Case Western Reserve University, Cleveland, Ohio

Susan Redline, M.D., M.P.H.
Case Western Reserve University, Cleveland, Ohio

To the Editor:

The use of data on self-reported race in health research has been highly debated. For example, Burchard et al. recently argued that important information on disease susceptibility may be derived from the use of data on self-reported race, whereas Cooper et al. cited Wilson et al., who argued that ethnic labels “are inaccurate representations of the inferred genetic clusters.” Cooper et al., however, ignored later work that identified limitations in the analyses of Wilson et al. — specifically, inappropriate classification of groups, the use of a suboptimal model for cluster identification, and reliance on only 39 microsatellite markers for cluster analyses. With larger numbers of markers, it was shown that genetically distinct groups can be almost completely inferred from self-reported race…

…With support from a U.S. Public Health Service grant, we applied an admixture analysis to a sample population in Cleveland. Participants were clearly separated into unique groups with the use of this genetic approach. Whereas 93 percent of self-reported whites were classified as having predominantly European ancestry, less than 2 percent of blacks were so classified. Only 4 percent who reported their race as black had predominantly African ancestry; yet, the admixture proportions of this group made it possible to separate the population into two groups, in which 94 percent of self-reported blacks and 7 percent of self-reported whites were classified as being of mixed race (Figure 1: Frequency Histogram Showing the Percentage of African Ancestry in a Population Living in Cleveland). The sharp peak at the left in Figure 1 indicates that there are many persons who have no African ancestry (i.e., the values correspond to those of self-reported whites), and the broad peak at the right indicates that most blacks are of mixed race and do not originate from any single population. Thus, self-reported race and genetic ethnic ancestry appear to be highly correlated as a dichotomy, with those who self-report as being black comprising, as expected from historical and cultural practices in the United States, a broad range of African ancestry…

Read the entire letter here.

Comparing Genetic Ancestry and Self-Described Race in African Americans Born in the United States and in Africa

Cancer Epidemiology, Biomarkers & Prevention
Volume 17, Issue 6 (June 2008)
pages 1329-1338
DOI: 10.1158/1055-9965.EPI-07-2505

Rona Yaeger
Herbert Irving Comprehensive Cancer Center

Alexa Avila-Bront
Department of Medicine
College of Physicians and Surgeons of Columbia University

Kazeem Abdul
Herbert Irving Comprehensive Cancer Center

Patricia C. Nolan
Department of Medicine
College of Physicians and Surgeons of Columbia University

Victor R. Grann
Department of Medicine
College of Physicians and Surgeons of Columbia University

Mark G. Birchette
Department of Biology
Long Island University, Brooklyn, New York

Shweta Choudhry
Department of Biopharmaceutical Sciences and Medicine
University of California-San Francisco, San Francisco, California

Esteban G. Burchard
Department of Biopharmaceutical Sciences and Medicine
University of California-San Francisco, San Francisco, California
 
Kenneth B. Beckman
Children’s Hospital Oakland Research Institute, Oakland, California

Prakash Gorroochurn
Department of Biostatistics
Columbia University Medical Center, New York, New York

Elad Ziv
Division of General Internal Medicine
University of California-San Francisco, San Francisco, California

Nathan S. Consedine
Department of Psychology
Long Island University, Brooklyn, New York

Andrew K. Joe
Herbert Irving Comprehensive Cancer Center

Genetic association studies can be used to identify factors that may contribute to disparities in disease evident across different racial and ethnic populations. However, such studies may not account for potential confounding if study populations are genetically heterogeneous. Racial and ethnic classifications have been used as proxies for genetic relatedness. We investigated genetic admixture and developed a questionnaire to explore variables used in constructing racial identity in two cohorts: 50 African Americans and 40 Nigerians. Genetic ancestry was determined by genotyping 107 ancestry informative markers. Ancestry estimates calculated with maximum likelihood estimation were compared with population stratification detected with principal components analysis. Ancestry was approximately 95% west African, 4% European, and 1% Native American in the Nigerian cohort and 83% west African, 15% European, and 2% Native American in the African American cohort. Therefore, self-identification as African American agreed well with inferred west African ancestry. However, the cohorts differed significantly in mean percentage west African and European ancestries (P < 0.0001) and in the variance for individual ancestry (P ≤ 0.01). Among African Americans, no set of questionnaire items effectively estimated degree of west African ancestry, and self-report of a high degree of African ancestry in a three-generation family tree did not accurately predict degree of African ancestry. Our findings suggest that self-reported race and ancestry can predict ancestral clusters but do not reveal the extent of admixture. Genetic classifications of ancestry may provide a more objective and accurate method of defining homogenous populations for the investigation of specific population-disease associations.

Introduction

Genome-wide case-control association studies provide a powerful tool for investigating possible genetic factors that may contribute to the health disparities observed among different racial and ethnic populations. Populations with different ancestral backgrounds may carry different genetic variants, and these may contribute to the variations in disease incidence and outcomes seen in specific racial and ethnic groups (1). Association studies can most easily identify disease-associated alleles when study groups are genetically similar, sharing a similar ancestral background (2). However, individual ancestry is not an easily assayed, simple category; consequently, race continues to be used as a proxy for genetic relatedness in clinical and other biological studies (3-6). There is currently no consensus on how best to examine or characterize different racial or ethnic groups when designing and conducting such studies.

Two main approaches have been used to approximate individual ancestry in biological studies: (a) using self identified race and ethnicity, which may capture common environmental influences as well as ancestral background, and (b) genotyping a panel of markers that show large frequency differentials between major geographic ancestral groupings (7, 8). Both approaches have limitations. Self-identified racial categories may not always consistently predict ancestral population clusters, and evidence suggests that it may take large sample sizes and numerous markers to describe genetic clusters that correspond to self-identified race and ethnicity groupings (9-11). Racial categories are also imprecise and inconsistent, because they may potentially vary within the same individual over time (12, 13). Furthermore, their use risks reinforcing racial divisions in society. On the other hand, more objective analyses that genotype markers that are highly informative for ancestry may not be economically practical and are limited by the requirement of serum or fresh tissue for DNA extraction. Genetically determined ancestry may not capture unmeasured social factors that may affect differences in health outcomes. There are also unique ethical challenges when linking biological phenotypes with genetic markers for specific racial groups, and caution must always be used when attributing biological differences (e.g., disease risk and treatment response) to different populations.

Understanding the ancestral background of study subjects is most important in genetic studies of admixed populations, such as African Americans, who represent an admixture of Africans, Europeans, and Native Americans (14). Genetic studies have shown that African Americans form a diverse group with percent European admixture estimated to range between 7% and 23% (14-16). Genotyping of self-identified African Americans participating in the Cardiovascular Health Study revealed that among self-reported Africans there are differences in genetic ancestry that are correlated with some clinically important endpoints (15).

…Discussion…

The African American cohort in our study had a mean of 15% European admixture, which is consistent with previous reports of a range of 7% to 23% European admixture among U.S. African Americans (14-16). Of note, the estimates of 4% European and 1% Native American ancestry in the Nigerian population is likely due to bias in MLE due to the limited number of markers. We found that among participants there was a significantly higher proportion of admixture and higher variability in admixture proportions in the U.S.-born African American cohort compared with a population that emigrated from Africa (that is, Nigerians; Table 3). The significant variation in individual ancestry estimates among the African American cohort suggests that this group, like the Cardiovascular Health Study African American cohort (15), represents a diverse population consisting of several subpopulations. For participation in the African American cohort, subjects identified both parents as African Americans who were born in the United States. Although data regarding grandparental race were not used to screen study participation, these data were collected through a three-generation family tree during administration of the questionnaire. In this study population, all African American subjects described that the race of at least three of their four grandparents was consistent with African ancestry. Individuals and society have historically classified children of mixed-race ancestry as African American, even when one parent is Caucasian, Asian, or Native American. For African Americans, this is a remnant of the ‘‘Jim Crow’’ laws and the ‘‘One Drop’’ rule or ‘‘Rule of Hypodescent.’’ Thus, identification as African American would still occur in cases where the parents and grandparents were of mixed-race ancestry. This could also contribute to the greater European admixture and greater admixture variability seen in the African American cohort…

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Patterns of gene flow between Negroes and whites in the US

Journal of Biosocial Science
Volume 8, Issue 4 (1976)
pages 309-333
DOI: 10.1017/S002193200001083X

K. F. Dyer
Department of Genetics
University of Adelaide, South Australia

A review of the pattern and magnitude of negro–white mating in the US is presented from the time of the earliest arrival of negroes in the American colonies until the present, using historical, demographic, census and genetic evidence.

The relative magnitude of negro male–white female matings compared to the converse are analysed in view of the different genetic outcomes of these two types of mating for X-linked genes. Contrary to many strongly stated opinions it is conclued from the historical evidence that, even from the earliest days of slavery, negro male–white female matings were a significant proportion of all negro–white matings. Census and demographic evidence suggests that their frequency increased so that from the time of the Civil War on they have formed a majority of inter-racial matings.

Genetic evidence based on estimates of the amout of admixture of white genes in a number of negro populations is considered. Estimates of admixture for the X-linked genes G6PD, and those for colour blindness are as high or higher than those derived from comparable autosomal genes.

Some observations on the total magnitude of negro–white mating, on the phenomenon of passing and on the relative socio-economic status of those involved are also made.

The implication of the findings on these phenomena for investigations and hypotheses concerning differences in intelligence and intellectual abilites between the races, particulary spatial ability which is thought to be strongly influenced by a gene on the X chromosome, are considered.

It is concluded that some of the assumptions made in proposing hypotheses regarding the origin and distribution of these abilities in the American negro are at variance with genetic, historical and sociological findings.

Migration and Race Mixture from the Genetic Angle

The Eugenics Review
Volume 51, Number 2 (July 1959)
pages 93-97

Sir Macfarlane Burnet, O.M., F.R.S., Director
Walter and Eliza Hall Institute of Medical Research

This paper was prepared at the request of the Department of Immigration for discussion by delegates at the Australian Citizenship Convention. The views expressed in it are those of the author and do not necessarily represent the official views of the Department.

From the long-term point of view, immigration is chiefly important to Australia for the overall changes that it will eventually make in the genetic character of our population. Every growing country that receives substantial immigration from other parts of the world is in a sense a melting-pot from which new combinations of body-build, of skin colour, and even of personality, may eventually emerge. The process is immensely complex and can only be described in broad outline. In many ways our description can be no more than an attempt to interpret the human observations in terms of genetic ideas that have been developed from the study of such very different animals as fruit ffies and mice. Yet the very fact that basically similar gentic laws are evident in the behaviour of mice, of fruit flies, and of bacteria, makes us confident that they are equally applicable to man…

…Advantages and Disadvantages of Race Mixture

Extensive reading has failed to locate a single example where it can be shown that hybrid races or individuals living under circumstances where no social disability attached to their condition, were demonstrably inferior to both parents. Where healthy typical individuals of each race are concerned, the offspring can be expected to show greater physical health than either and-though here the evidence is slighter-a greater likelihood of exceptional mental ability.

Serious attempts have been made to show that where different racial groups mingle, there the likelihood of an outcropping of genius is highest. Kretchmer considered that where the Alpine race containing Neanderthal genes made contact with Nordics in the German speaking parts of Europe, there had appeared an exceptional number of outstanding men. Toynbee generalized that “the geneses of civilization require creative contributions from more races than one”. It seems to be the general rule that there is a lag period of a few centuries between the beginnings of race mixture in a given region and the full flowering of a new culture or civilization.

There are potential genetic disadvantages of race mixture and it is probably true that particularly in later generations than the primary hybrid, occasional individuals with discordant characters, e.g. teeth over-large for the jaw that carries them, can be seen. It has not been shown decisively that such discordancies are more frequent than in people not descended from recent racial mixture…

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Color, Race, and Genomic Ancestry in Brazil: Dialogues between Anthropology and Genetics

Current Anthropology
Volume 50, Number 6 (2009)
pages 787-819
DOI: 10.1086/644532

Ricardo Ventura Santos, Professor of Biological Anthropology and Public Health
Oswaldo Cruz Foundation
also Associate professor of Anthropology
National Museum, Rio de Janeiro, Brazil

Peter H. Fry, Professor
Federal University of Rio de Janeiro, Departamento de Antropologia
Instituto de Filosofia e Ciências Sociais/UFRJ, Largo de São Francisco de Paula 1

Simone Monteiro, Senior Researcher
Oswaldo Cruz Institute

Marcos Chor Maio, Senior Researcher
House of Oswaldo Cruz
Oswaldo Cruz Foundation

José Carlos Rodrigues, Professor
Fluminense Federal University
also Associate Professor
Catholic University

Luciana Bastos-Rodrigues
Department of Biochemistry and Immunology at the Institute of Biological Sciences
Federal University of Minas Gerais

Sérgio D. J. Pena, Professor of Biochemistry and Immunology
Institute of Biological Sciences
Federal University of Minas Gerais

In the contemporary world, “race” narratives are so multifaceted that at times, different views of the concept appear mutually incompatible. In recent decades biologists, especially geneticists, have repeatedly stated that the notion of race does not apply to the human species. On the other hand, social scientists claim that race is highly significant in cultural, historical, and socioeconomic terms because it molds everyday social relations and because it is a powerful motivator for social and political movements based on race differences. In this paper we present the results of an interdisciplinary research project incorporating approaches from genetics and anthropology. Our objective is to explore the interface between information about biology/genetics and perceptions about color/race in Rio de Janeiro, Brazil. We argue that the data and interpretation of our research resonate far beyond the local level, stimulating discussion about methodological, theoretical, and political issues of wider national and international relevance. Topics addressed include the complex terminology of color/race classification in Brazil, perceptions about ancestry in the context of ideologies of Brazilian national identity, and the relationship between genetic information about the Brazilian population and a sociopolitical agenda that turns on questions of race and racism.

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Racial Identities, Genetic Ancestry, and Health in South America: Argentina, Brazil, Colombia, and Uruguay

Palgrave Macmillan
October 2011
272 pages
Includes: 10 pages of figures, 10 pages of tables
5.500 x 8.250 inches
ISBN: 978-0-230-11061-8, ISBN10: 0-230-11061-4

Edited by

Sahra Gibbon, Wellcome Trust Fellow
Department of Social Anthropology
University College London

Ricardo Ventura Santos, Professor of Biological Anthropology and Public Health
Oswaldo Cruz Foundation
also Associate professor of Anthropology
National Museum, Rio de Janeiro, Brazil

Mónica Sans, Associate Professor and Director of the Biological Anthropology Department
University de la Republic in Uruguay

This unique edited collection brings together biologists, geneticists, and social and biological anthropologists to examine the connections between genetics, identity, and health in South America. It addresses a wide range of theoretical issues raised by the rapid changes in the field of genetic sciences. Contributors come from Brazil, Colombia, Argentina, Uruguay, the UK, and the United States, providing a comparative cultural perspective for scholars, researchers, and students.

Table of Contents

• Preface; N.Redclift
• PART I: DOING AND DEFINING “BIO-CULTURAL” ANTHROPOLOGY AS APPLIED TO GENETICS
  • Anthropology, Race, and the Dilemmas of Identity in the Age of Genomics; R.Ventura Santos & M.Chor Maio
  • The Inexistence of Biology Verses the Existence of Social Races: Can Science Inform Society?; S.D.J.Pena & T.S.Birchal
  • Ethics/Bioethics and Anthropological Fieldwork; A.L.Caratini
• PART II: ADMIXTURE MAPPING AND GENOMICS IN SOUTH AMERICA AND BEYOND
  • Admixture Dynamics in Hispanics: A Shift in the Nuclear Genetic Ancestry of a South American Population Isolate; L.Ruiz
  • Pharmacogenetic Studies in the Brazilian Population; G.Suarez-Kurtz & S.D.J.Pena
  • Admixture Mapping and Genetic Technologies; B.Bertoni
  • The Significance of Sickle Cell Anemia within the Context of the Brazilian Government’s ‘Racial Policies’ (1995-2004); P.H.Fry
• PART III: GENETIC ADMIXTURE HISTORY, NATIONHOOD AND IDENTITY IN SOUTH AMERICA
  • Gene Admixture and Type of Marriage in a Sample of Buenos Aires Metropolitan Area; F.R.Carnese
  • Ethnic/Race Self-Adscription, Genetics, and National Identity in Uruguay; M.Sans
  • Forced Disappearance and Suppresion of Identity of Children in Argentina: Experiences after Genetic Identification; V.B.Penchaszadeh
  • Molecular Vignettes of the Columbian Nation: The Place of Race and Ethnicity in Networks of Biocapital; C.A.Barrigan
• Afterward/Commentaries; R.Rapp, T.Disotell, M.Montoya & P.Wade

Eugenics and Mongrelization [Letter and Response]

The Eugenics Review
Volume 32, Number 1 (April 1940)
pages 28-30

To the Editor, Eugenics Review

SIR, In order that the eugenics movement shall advance successfully, the eugenics organizations must dissociate their endeavours from the widespread propaganda for race amalgamation and mongrelization. There is little wisdom in breeding selectively among individuals if the results are to be nullified by indiscriminate mixing of the races. Nearly all the arguments against the existence of different races are coming from spokesmen for races that desire admixture to, and absorption by the white race, or Aryan race, using the name in the newer adapted sense. The arguments have utterly failed to change the truth that there are at least three great races-the whites, or Aryans; the Mongolians; and the Negroes. The Jews may be regarded as a sub-race that in some degree, or at least in some countries, may be absorbed by other races.

There has been vastly less race mixture in the northern hemisphere than the amalgamation exponents contend. The United States is not a nation of mixed races, as some writers allege. There has been a small admixture of American Indian and Mexican in some of the western states, and a small admixture of Jews in some of the cities. There are about twelve million Negroes, who have a small fraction of widely diffused white blood, due mainly to miscegnation on the southern plantations before the Civil War. But there is practically no Negro blood in the one hundred and ten million whites, who are almost purely of European descent and have absolutely no intention of amalgamating with the Negroes.

The white race is unquestionably uniquely beautiful and is in many respects of superior intelligence. To mix the white features with other races would destroy the white beauty for ever. The white race should maintain its purity and should further develop its characteristics…

…The mixing of races would produce mongrels lacking the distinctive qualities and values of all races. Eugenics means, not only breeding from the superior and eliminating the unfit among individuals, but also similar procedure as between the races. The white race idealizes a pure white race and further development of its characteristics. There can be no idealization of a mongrel humanity, except among races that desire admixture with whites and thus acknowledge a belief in their own inferiority. This has been the almost universal attitude of the white race, at least in the United States. The cruel persecution of the Jews in Germany caused a temporary reaction in favour of race solidarity, but with the adjustment of the Jewish problem in some manner, the real attitude of the white race will become more outspoken and unmistakable. The eugenics organizations must act along these lines, else their efforts will fail and new organizations will be formed to strive for the true eugenic ideals.

CYRUS H. ESHLEMAN
1510 Lincoln Avenue
Lakewood, Ohio, U.S.A.

[Response from the Editor]

Some of the statements in the above letter must not be allowed to pass without comment. The implication in the first sentence, that the eugenics movement associates its endeavours with “propaganda for race amalgamation and mongrelization” is, as far as this country is concerned, a travesty of the facts. We should be much surprised to learn that it is true of the eugenics movement in any country. The views of this Society, as set forth in its Statement of Aims and Objects, is  “that further knowledge of the results of such crosses is needed in order to distinguish between the effects of unfavourable hereditary and environmental influences and to frame a practical eugenic policy.” This does not mean that we do not share Mr. Eshleman’s disquietude at the “indiscriminate mixing of the races,” but we should regard it as a nice question whether that is any more undesirable than the indiscriminate mating of persons belonging to the same race.

The assumption in the second paragraph would almost certainly be rejected by most competent anthropologists to-day. The plain fact that there is no such thing as an Aryan race is in no way altered by the device of using “Aryan” in its ” newly adapted sense.” The only assemblage of human beings to which this purely linguistic term may be applied is the heterogenous body of ethnic and national groups who share the common peculiarity of speaking the Aryan or Indo-European languages. The “great white race” represents in fact a somewhat elastic conception, but however arbitrarily its limits are defined it is difficult to see how they could exclude the majority of Jews. The fact, however, that they would certainly not include the indigenous Jewish communities which exist in both Abyssinia and China is an indication of how far-to quote Huxley and Haddon—”the term Jew is valid more as a socio-religious or pseudonational description than as an ethnic term in any genetic sense.”

The claim that “there has been vastly less race mixture in the northern hemisphere” than is sometimes alleged, may be questioned in the light of some data which have been submitted to us for publication by Mr. J. C. Trevor, formerly one of the Eugenics Society’s Darwin Research Fellows and now University Lecturer in Anthropology at Cambridge. In Mr. Trevor’s paper, for which we hope to find room in our next issue, the ratio of mixed bloods (i.e. persons of partly European and partly non-European stock) to the total population of the United States is given as slightly over 7 per cent, Admittedly this figure can at best be only an approximation, but including as it does in its basis Kuczynski’s statement that to count 6o per cent of the negro inhabitants of that country as mulatto would be “a most conservative estimate,” it is more likely to understate the facts than overstate them. It is noteworthy that according to an eminent American scholar, the number of negroes of full blood was unduly exaggerated in the 1920 U.S. census, the last in which an attempt was made to assess the mulatto element by itself. And it need hardly be added that the familiar phenomenon of “passing for white,” with its inevitable consequences, must not be overlooked in examining the contention that “there is practically no negro blood in the one hundred and ten million whites.”…

Read the entire letter and response here.

The Enculturated Gene: Sickle Cell Health Politics and Biological Difference in West Africa

Princeton University Press
2011
368 pages
6 x 9; 7 halftones. 1 line illus. 4 maps
Paper ISBN: 9780691123172
Cloth ISBN: 9780691123165
eBook ISBN: 9781400840410

Duana Fullwiley, Associate Professor of African and African American studies and of Medical Anthropology
Harvard University

In the 1980s, a research team led by Parisian scientists identified several unique DNA sequences, or haplotypes, linked to sickle cell anemia in African populations. After casual observations of how patients managed this painful blood disorder, the researchers in question postulated that the Senegalese type was less severe. The Enculturated Gene traces how this genetic discourse has blotted from view the roles that Senegalese patients and doctors have played in making sickle cell “mild” in a social setting where public health priorities and economic austerity programs have forced people to improvise informal strategies of care.

Duana Fullwiley shows how geneticists, who were fixated on population differences, never investigated the various modalities of self-care that people developed in this context of biomedical scarcity, and how local doctors, confronted with dire cuts in Senegal’s health sector, wittingly accepted the genetic prognosis of better-than-expected health outcomes. Unlike most genetic determinisms that highlight the absoluteness of disease, DNA haplotypes for sickle cell in Senegal did the opposite. As Fullwiley demonstrates, they allowed the condition to remain officially invisible, never to materialize as a health priority. At the same time, scientists’ attribution of a less severe form of Senegalese sickle cell to isolated DNA sequences closed off other explanations of this population’s measured biological success.

The Enculturated Gene reveals how the notion of an advantageous form of sickle cell in this part of West Africa has defined–and obscured–the nature of this illness in Senegal today.

Table of Contents

• List of Illustrations
• Preface
• Acknowledgments
• Chapter One: Introduction: The Powers of Association
• Chapter Two: Healthy Sicklers with “Mild” Disease: Local Illness Affects and Population-Level Effects
• Chapter Three: The Biosocial Politics of Plants and People
• Chapter Four: Attitudes of Care
• Chapter Five: Localized Biologies: Mapping Race and Sickle Cell Difference in French West Africa
• Chapter Six: Ordering Illness: Heterozygous “Trait” Suff ering in the Land of the Mild Disease
• Chapter Seven: The Work of Patient Advocacy
• Conclusion: Economic and Health Futures amid Hope and Despair
• Notes
• References
• Index

Only Skin Deep? The Harm of Being Born a Different Colour to One’s Parents: A (a minor) and B (a minor) by C (their mother and next friend) v A Health and Social Services Trust [2010] NIQB 108; [2011] NICA 28

Medical Law Review
Volume 19, Issue 4 (Autumn 2011)
pages 657-668
DOI: 10.1093/medlaw/fwr029

Sally Sheldon, Professor of Medical Law and Ethics
University of Kent

The complainants, A and B, were twins born as a result of IVF treatment involving donated sperm provided by the Defendant Trust to their mother. While the children’s parents were white, the twins had darker skin than either of them and different skin colour to each other, a difference that had become more marked as they had grown older. It transpired that while the Trust’s normal practice would be to request only sperm from ‘Caucasian’ or ‘white’ donors for a white couple, in this instance sperm from a ‘Caucasian (Cape Coloured)’ donor had mistakenly been used. The implication of this error was that while the sperm donor was white, there was no guarantee that his genetic children would also be so. By the time the action reached the courts, the twins were eleven years old.

The Trust admitted liability to the parents. However, it opposed the action brought on behalf of the twins, in which they alleged three broad kinds of harm. First, because of their colour, the twins had become ‘the subject of derogatory comment and hurtful name calling from other children, causing emotional upset’. Secondly, they had been the subject of adverse and hurtful comment about the colour of their skin and their physical dissimilarity from each other, on the one hand, and between themselves and their parents on the other. This had led them to question their parents about whether they were adopted. Thirdly, should either twin go on to have a child with a partner of mixed race, any child born to them was likely to have a different skin colour from either parent.

The court proceedings raised, by common agreement of the parties, a number of legal issues: first, the existence and nature of a duty of care owed to A …

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The myth of the melting pot

Biodemography and Social Biology
Volume 1, Issue 4 (1954)
pages 248-251
DOI: 10.1080/19485565.1954.9987204

David C. Rife
Institute of Genetics
The Ohio State University

Elton F. Paddock
Institute of Genetics
The Ohio State University

Myths are fictional legends, but more often than not they carry elements of truth. Popular beliefs concerning the results of racial mixture may be classed as the myth of the melting pot According to this myth, the mixture of races is analogous to the process of manufacturing alloys. There is actually a great deal of truth in this analogy, although the true nature of alloys is frequently misunderstood.

When molten copper and zinc are thoroughly mixed in the proper proportions, brass will be produced. Brass, bronze, and other alloys are intimate mixtures of two or more pure metals. The ideal alloy is one which combines the desired qualities of two or more metals in what appears to be a homogeneous blend.

The appearance of homogeneity is superficial, however, as the alloy is essentially a physical mixture, not a chemical compound. Brass, for example, is a mixture of particles of pure copper and pure zinc, the size of the particles varying from atoms to tiny crystals. The result of a mixing of two races is analogous to the metallurgical melting pot in that the mixing does not result in the elimination of variability. It differs in that the end product in the human melting pot is a grosser mixture, the variation within mixed populations being more readily visible than in the metallic alloy. Concepts to the effect that either type of melting pot produces a new homogeneous product are purely fictitious.

The myth of the human melting pot is founded on the assumption that the hybridization of different human populations will eventually result in the elimination of biological differences. According to this way of thinking mankind will eventually be characterized by a uniform shade of skin color, hair form, and various other physical characteristics, which now vary from one ethnic group to another. There can be no question but that barriers between human races are rapidly being eliminated, owing to modern transportation, education, and communication. Today it is difficult to find “pure” racial groups. In most parts of the world many cultural barriers to understanding and cooperation are on the way out. But what about genetic variability? Is it tending to become less?

The answer is “no.” Genes, the particles of heredity, do not lose their identities but maintain them over an indefinite number of generations, regardless of what other genes they may be associated with. This principle is the essence of the classical discoveries made by Mendel almost a century ago. Mixture of races neither increases nor decreases the total genetic variability in mankind. It brings about an increase of  individual variability.

Mixtures of Negroes and Whites provide an excellent example of this principle. The first generation offspring are intermediate or mulatto. But if these mulattoes marry other mulattoes of similar origin, their offspring will exhibit subtly varying degrees of pigmentation, ranging from the dark brown of Negroes to the light pigmentation of Whites. The genes have maintained their individuality from one generation to another. The mixed population will have much greater variability with respect to…

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