Date: December 04, 2018 03:57PM
University of Utah professor of human genetics Aaron Quinlan said when it comes to tracking ethnicity via DNA, it's important to distinguish between a person's genealogical records and genetic evidence.
"Our sense of genealogy is a narrative which can be supported with historical and family records," Quinlan said. "And, while many people think we can track DNA back many generations, we really can't draw useful information past about seven generations."
Quinlan explained that any individual's genetic makeup represents about half a contribution from each parent. One tier up the family tree, and each of those parents is getting half of their genes from a parent, and so forth. Trying to assemble a picture of our ethnic histories, based on that tracking, gets hazy very quickly.
"The way I like to think about it is like a patchwork quilt," Quinlan said. "The further we reach back, the smaller the patches of genetic information remains. Companies like Ancestry and others are trying to compare one patchwork to other patchworks."