Well, firstly racial studies demonstrating the need to protect the white race was kind of this guy's specialty... https://en.wikipedia.org/wiki/J._Philippe_Rushton
But onto the topic at hand, the original theory was based on an incorrect understanding of genetics, where a child's genes were based on both the parent and the "ancestors". The reality is that children inherit directly from parents, including some genes that were unexpressed, which can cause changes. But they're still more likely to be smart. https://en.wikipedia.org/wiki/Regression_toward_the_mean#His...
If regression to the mean dominated 100% of the time, evolution would not be possible. http://biology.stackexchange.com/questions/41982/regression-...
Over time if you keep breeding smart people, you can expect to see smart children. If you did this and ignored ethnicity, you'd overtime breed yourself a new "race".. after all how do ethnicities form in the first place but by separation, drift, and natural selection? Also if you did this long enough you might breed superhumans, but I suspect that genetic engineering would come first and beat you to the punch ;)
> I brought race because that was the topic at hand and because we are talking biology here (reproduction)
I keep bringing it back to America since that's all I know, but race in America is more social construct than biology, and keeps changing over time. For instance the Irish, Italians, or eastern europeans were at some point not considered white. In other countries, race is seen differently as well (though this has changed due to western media)
White today includes a lot of people who have historically not been considered white, and IQs will vary by those subgroups. For instance: https://en.wikipedia.org/wiki/Ashkenazi_Jewish_intelligence is measured to be especially high. (Also randomly, I find it especially strange that the stormfront crowd seems so eagar to separate themselves from jews. I never understood that)
Anyways, the desire for protectionism seems like a never ending quest to me, since we will always find ways to divide ourselves. Even when america was mostly european, this sentiment still existed, and was directed at the Irish, italians, jews, etc.
https://www.google.com/search?q=anti+jewish&source=lnms&tbm=...
What we call race has formed mostly for social reasons: we look similar enough, share enough cultural similarity, and we're under attack by the "other" so let's band together. Asians in asia all hate each other. They all get along in the US. Pakistanis and Indians don't get along in their home countries. They're best friends in the US. Same story: you arrive in the US, you band together with people most like yourself to help you when faced with pressure.
Edit: I'm sorry you're receiving downvotes even though you're being civil. I suspect that this is the type of "under attack" that I mentioned in my last paragraph that gives rise to strong same-race stickiness to begin with.