I got a bit of a spark from Chiam's statement in the "Ask JTF" segment of last week when he said that he did not think that any group of people was "genetically inferior".
You do bring up a good point here. You are correct in that Chaim doesn't believe culture has a genetic component. He believes that cultural characteristics are a matter of choice, not genetics. Personally, this is one area where I disagree with him.
I disagree as well. Culture and genetics can't be separated. Our culture largely grows from our natural dispositions.
But that is not the same as talking about "genetic inferiority." This is a value judgement. Define your terms - and one group will be better, another worse. For example, are you talking about running, physical strength, musicality, or solving mathematical equations?
At the same time, I think that all groups have an equal capacity to make moral choices. Morality is not pre-destinied by one's genetics. It is true, for example, that blacks are genetically more aggressive (there have been studies to demonstrate it). Aggressive behavior has a hormonal component. But being more aggressive does not have to automatically imply that you behave like a criminal. You can use your aggression and physical strength in a moral way, for example summon what I call a "holy rage" to fight injustice.
I think that all people are equal in G-d's eyes as moral agents. They have an initial equal human worth and equal responsibility to behave morally. This is where equality begins and ends, in my opinion.