People are people, but I think there’s plenty of evidence that beyond basic nutrition nature is stronger than nurture in driving intelligence—and there’s not much point to denying that apparent truth.
When you are dealing with traits determined by multiple genes that sort separately during reproduction, what you wind up with will be highly variable. That's why separate children from the same parents look different and often have very different personalities. Of course, as we've discussed, the 'nurture' aspect also plays a significant role.
There are no groups of people on the planet who are inherently smarter than others. That kind of thought process led to the myth of Aryan superiority that Hitler used as propaganda and that led to a world war and the deaths of millions - including millions of Jews in one of the most inhumane and hateful atrocities ever seen.