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promonk t1_ishdkr1 wrote

Reply to comment by Kandiru in When it's said 99.9% of human DNA is the same in all humans, is this referring to only coding DNA or both coding and non-coding DNA combined? by PeanutSalsa

When you say "more common variants," common in what way?

I'm fascinated by the idea of a "reference human."

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Kandiru t1_ishg2ww wrote

Say a certain position is a A for 90% of people, but a C for 10%. The A variant is more common than the C.

So when the reference had previously had a C there, in a later version it's often been changed to the most frequent base.

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promonk t1_ishu3eb wrote

I get that. What I'm curious about is sampling. 90% of which population? Is it 90 of some college-age kids being paid a hundred bucks for a cheek swab? Or is it drawn from a broad swathe of demographics and locations?

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