maybe some groups have a genetic limitation to the likely of above average intelligence.
There is no maybe, every study that has ever looked into this since the dawn of science has confirmed this. Hell you don't even have to ask science, every average Joe on the street knows this already from life experience.
It's just in the last ~20 years that political correctness mass hysteria has gripped academia and the media to where it's become a thoughtcrime to think any other thought than that all races are exactly equal in every aspect except maybe skin melanin level.
And it's just the United States and a couple of other Western European countries afflicted with this weirdness. If you were to go to, say, Japan or Russia and say to a scientist, "Some races have higher genetic disposition for intelligence than others", he will most likely shrug and say "Yeah, so what?"
But just in case you're young and everything you've ever read has been sanitized by the Academic Department of Purethought: the highest average IQ of any human race/group belongs to Ashkenazi Jews.