Tuesday, September 14, 2021

DoesN't Add Up


Another update for my fellow 23andMe participants: My mom's results just came in -- don't tell her, it's a birthday surprise! -- and it bolsters what I have been saying all along: Hers are exactly as our family history shows -- father was Lithuanian, mother was German -- which then raises the question why my results were "updated" in a way that eliminated half of her family DNA. (It now somehow believes I am 65% Irish, even though she's 0%.) Someone told me that Ancestry.com was doing a new algorithm overhaul. Wondering if 23andMe will too, preferably one that will put it back the way it was when mine was correct.


This is interesting. Although they haven't changed the way their algorithm works back to the way it started, ancestry compositions are fluid and just today my erroneous Irish percentage dropped from 65% to 60.3%. It's still incorrect -- you get half your DNA from each parent -- but it does show things moving (back) in the correct direction. What's disappointing, though, is that because 23andMe detects that this woman is my mother -- and we're even linked to each other's profile -- why wouldn't it just autocorrect the error, knowing there's no way I could be anything more than 50% Irish?


Edgar_Carpenter said...

These companies compare your DNA to the DNA they have collected in other places around the world. So they are saying that you are 60.3% related to people living in Ireland today. Since people have been moving more and more freely around the world in the last few centuries, it's entirely possible that 60.3 is accurate now for your own genetic makeup.

Additionally, your genetic inheritance from your parents is not as simple as 50 50. Crossover and recombination happen, so the markers they check in your DNA may not be exactly a 50% match to your mom.


Kenneth M. Walsh said...

@Edgar: Thanks. I believe what you're saying, yet still can't figure out why mine changed from making sense to not making sense ... or why everyone else I know who has done it has an obvious division between father and mother, as does my mom. Color me perplexed.