race, racial differences and racial categories are arbitrary and can't be properly defined?

I show them the studies on genetics which prove that the five "races" of humanity are more genetically distant from one another than different species in the animal kingdom are. Pic related.

culture isn't influenced by race?

I talk about the concept of instinct, which mainstream "scientists" say doesn't apply to humans, but which magically applies to all other animals. Physical differences drive behavioral differences, simply because of the different range of behaviors afforded to those with different physical capabilities. Behavioral differences drive social differences, as groups which uniformly cannot perform X due to physical incapability will not form societies that include X.