This is simply false. We know for a fact that humans have an in-group bias. Studies have shown that even infants and toddlers are biased toward their own in-group.
https://phys.org/news/2017-04-infants-racial-bias-members.ht...
https://time.com/67092/baby-racists-survival-strategy/
If what you claim is true, we would never have had miscegnation laws. Most people in the world wouldn't encourage marrying their own kind.
Just think about it. If people naturally favored the out-group ( people who look different ), racial/ethnic groups and diversity wouldn't exist. Blue eyes and blonde hair wouldn't exist because they are recessive traits. We wouldn't have any diversity because ethnic/racial groups require in-group bias to exist. The fact that we have black people, white people, indian people, chinese people, etc shows that in-group bias is the norm.
People naturally find their own kind and traits to be attractive. We know it's innate since it exists in babies. To find out-group features to be desirable requires external pressure - media, education, etc.
Edit: Since so many here are downvoting science because of their political agenda...
"We Choose Friends Who Are Genetically Similar to Us"
https://www.smithsonianmag.com/smart-news/we-choose-friends-...
"I like your genes: People more likely to choose a spouse with similar DNA"
https://www.sciencedaily.com/releases/2014/05/140519160716.h...