I dont think so. Im no expert on biology or antrho stuff but i think i remembered reading once that mixing bloodlines can help prevent birth defects?

and another reason is you can make some beautiful babies and people when mixing different races. like Asian and blacks, or latino and Caucasian, what have you. besides we are all human beings and evolved from the same original group of peoples so their should be no partitions between us. god bless.

There are downsides to BORDERS. If we didn't have borders there would be , eventually, ONE culture. That would remove 90% of the causes of war!

Wait, we'd still have religions ......

Culture is a very complex subject. I assume that by culture "mixing" you are referring to mixed culture kids, and not cultural appropriation. Of course there's nothing wrong being raised into an amalgamation of cultures, no matter how funny your memes try to be.