It's retarded to make the claim that any member of one abstracted genetic race procreating with a member of another abstracted genetic race will guarantee that the children created will be more intelligent or healthier by default. In fact it's extremely retarded.
Hybrid vigor is thoroughly unstudied in humans and the majority of our understanding of the topic comes from applying that understanding to humans. People who talk about hybrid vigor in humans don't seem to realise that heterosis really only applies to biological entities that are extremely inbred, like dogs or flowers. In other words, race mixing does not produce healthier offspring unless one of the parents is extremely inbred which is very rarely the case in the modern age. Even throughout history it was only really found in nobility.
Iceland has a population so small that you have to check with the government whether the person you're dating is your cousin or not and yet they're still not classed as inbred and have a healthy population.
The other side of the same coin is of course outbreeding depression. There are few examples of outbreeding depression in humans but this is likely due to the fact that up until this point in time there has been little mixing of an extent great enough to cause outbreeding depression, although this is changing so we may see it in the future.
Also, genes are shown to not be simply static entities that work in isolation from one another and simply happen to create a human. They work together and are intrinsically linked to the nature of the human. The psychology that stems from the genetics of an individual when extrapolated out to a population of similar genetics subsequently explains the emergence of cultures, societies, languages etc. This likely explains why individuals who have parents who are considered to be from seperate parents have higher levels of mental health issues. Although it could also be environmental.
