People should only be self-described.
Instead of trying to force a category on someone, you should ASK THEM if they identify with some proposed generalized type and or label.
Forcing a category on someone (that they do not personally self-describe as) is almost always an AD HOMINEM ATTACK.
If you insist that labels can be used to people who self-describe, you'll get more grifters and liars who pretend to be something they're not. For example, if you don't go to church, and you don't believe in God, and you don't know anything about the Bible, chances are you're not a Christian, even if you describe yourself as such.
In practical terms, it doesn't matter how many or how few "genetic markers" there are.
Humans cannot detect "genetic markers".
And discrimination, not only based on skin-tone, but also on language and culture and religion have existed for millenia, certainly long before anyone even considered "genetic markers".
For determining race, it matters a lot how many markers there are because using fewer than 30 leads us to faulty conclusions about the validity of human races. Using genetic markers in the first place is to demonstrate that human races are a valid concept, and aren't just something some 'racist' made up.
I agree that racial discrimination has existed long before our time, and the overwhelming majority of humans don't discriminate due to loci/SNP data collections. I'm just arguing that these people are inadvertently correct about different people being genetically different, sometimes to the point of being a different race.
BLUE POWER
PINK POWER
GREEN POWER
You've going to have to explain this one to me, lol.