Before Arguing About DNA Tests, Learn the Science Behind ThemPosted in Articles, Health/Medicine/Genetics, Media Archive, Native Americans/First Nation, Politics/Public Policy on 2018-10-25 00:51Z by Steven |
Before Arguing About DNA Tests, Learn the Science Behind Them
The New York Times
2018-10-18
 Senator Elizabeth Warren’s DNA test results indicated that she had a Native American ancestor several generations ago. Bridget Bennett for The New York Times |
Our genetic code cannot be treated as a matter of simple fractions.
People have always told stories about their ancestral origins. But now millions of people are looking at their DNA to see if those stories hold up. While genetic tests can indeed reveal some secrets about our family past, we can also jump to the wrong conclusions from their results.
The reception of Senator Elizabeth Warren’s DNA results is a textbook case in this confusion…
…Slavery, too, led to an obsession with increasingly tiny fractions of ancestral blood, reaching the absurd extreme of the “one drop” rule. A single black ancestor — no matter how far back in the family tree, no matter how tiny the mythical drop of blood he or she contributed — was enough to make a person black…
…But DNA is not a liquid that can be divided down into microscopic drops. It’s a string-like molecule, arranged into 23 pairs of chromosomes, that gets passed down through the generations in a counterintuitive way.
Eggs and sperm randomly end up with one copy of each chromosome, coming either from a person’s mother or father. In the process, some DNA can shuffle from one chromosome to its partner. That means we inherit about a quarter of our DNA from each grandparent — but only on average. Any one person may inherit more DNA from one grandparent and less from another.
Over generations, this randomness can lead to something remarkable. Look back far enough in your family tree, and you’ll encounter ancestors from whom you inherit no DNA at all…
Read the entire article here.