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Genetic Linkage

How DNA Ancestry Testing is Like the Wheel of Fortune: Filling in the Blanks

I'm a curious hybrid, a geneticist and an "NPE" – "not parent expected" – individual. My few posts about it, such as here and here, were from January, when I thought I had only one half-sibling. The discovery of others, some of whom know they were donor-conceived (DC), more or less confirms half of my origin.

 

So I wondered, on what percentage of a human genome's 3.2 billion DNA bases do the consumer DNA ancestry companies base these deductions that can shatter lives?

 

Do some tube-spitters and cheek-swabbers assume entire genomes are compared? No, not for $100, just yet. Others might not know what SNPs are, the  single-DNA-base markers that align in haplotypes on chromosomes and are used to match people, the algorithms trained on known relationships. With millions of people taking ancestry tests, the associations used in the matches are quite robust.

 

But I thought I'd do a small calculation to clarify what's probed when you plop your genetic essence into the mail, and how it represents an individual.

 

 

To continue reading go to my DNA Science blog at Public Library of Science.

 

 

 

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