Late to the thread, but my view on being "dumb" in general, even if you have the pre-req's knowledge and ability are different things. Most people, in my opinion, are smart enough to understand and apply just about any complex subject or topic. Being smarter just means you can "compute" and understand or apply the subject in question faster than others.

In the end, what we prioritize and how much time is available for us to tackle different subjects is the biggest limitation, not genetics or luck. Art and entertainment heavily influence these things.