The genetic testing done by 23 and me or ancestry are not accurate or reliable enough, and there’s very little to demonstrate any of the medical “insights” they claim are in fact accurate.

As for using DNA to determine ancestry mental relations get very dicey out past immediate lines- and even then, you will only share between 4-23% of any specific great grandparent’s dna.

Any specific grandparent, you inherit on average 25% of their dna- but this all depends on the genetic roll of the dice- usually between 20-30%, and when it comes to cousins; you might not actually share any DNA at all.

Because of how recombination works, you get a random mishmash from your parents.

Further, they way they figure ancestry in a larger frame is asininely stupid and ignores a simple fact that people generally don’t worry about interracial marriages nearly as much as supremacists would have you believe.

It’s most likely they didn’t even compare dna between you and your cousin, instead pulling records search and seeing you share a grandparent.

Finally, using dna to determine ancestry says absolutely nothing of value. Your culture is not determined by genetics; and. Either was theirs. Cultural heritage is not something that can be parsed from DNA.