IQ certainly plays a part, but I also agree with Jeff that culture (and in my opinion, economic class) has a lot to do with it. This will be a bit disjointed, but it will get somewhere.
Thanks appreciate it. It's not vomit at all, I actually read longer posts

Differences in brain function would be more related to emotional processing than IQ, but I know IQ in sub Saharan Africa is extremely low. I agree it mostly culturall though and not racial.
What you call emotional processing is also dictated by genes. IMHO. And OF COURSE environment and culture also plays a part, as does your moms diet during pregnancy and your diet growing up, but in developed countries it's relatively minor compared to the genetic impact. Think about this: there are plenty of studies comparing adopted twins who were separated and grew up in very different environments, sometimes on different continents. And what they have found is that IQs were pretty much identical. And often little things like music preferences were identical too, same favorite artists, seemingly showing how genes dominate over cultural impacts.
Another interesting thing is related to the "time preference" I mentioned earlier. Little children's development is often tested by measuring their ability to delay gratification. For example, a child is told it can either have one piece of candy now or three if they wait one hour. Black children more often choose option one. What's noteworty is that black childrens IQ is actually higher up to a certain age, forget what it was. Often criminals have this inability to delay gratification, they want the stimulus right now. We shouldn't prejudge a certain individual, but many would argue that it's critical to note average differences, especially when designing social programs.
Just assuming we are all equal and unwritten books when born is a leftist, liberal idea. Just a note to those here who hate the libturds. They say conservatives see the world as it is and libturds as they want it to be. But on certain subjects this is disregarded...