I completely disagree with this oversimplified statement. You look different from your best friend, your girlfriend, the taxi driver, and a turtle. Those are phenotypic traits determined by a complicated sequence of Hox gene expression and transcription factors that shape all of us. The new science of epigenetics/Evo-devo is where you need to look for the answers to these questions. We don't look the same, and our brains are not the same, they are not tabula rasa. Just like some people have big noses and little hands, some people have big anterior cingulates and little red nucleus's. It's OK, it doesn't mean that anyone is more special than anyone else. It does, though, mean that some people have a better natural proclivity for math and some for painting. What you're exposed to in your first years of life have an influence but it's not as influential as the complicated process through which progenitor neuroepithelial stem cells time their delays to create the areal divisions of the cortex. These processes are different in different individuals and yield different local areal dynamics in relation to global brain function.I agree with this, which is a restatement of the old "Tabula Rasa" view. Whether or not you become a math or art or music adept has more to do with how you're stimulated in the first years of life than anything else.
How these areal dynamics play out is currently what cutting edge neuroscience is investigating right now. We've recently had a big surge of data into the literature from fMRI studies and others but its still a pioneering area of research so its hard to make definite conclusions. I personally have found, though, that a safe haven for generalization is the of the cliche left brain right brain dichotomy. I know this because I stink at math no matter hard I try but I can sing and write one heck of a song. I don't why, but I'm guessing my ancestors liked to sing and dance more than they did to measure fenced yards. I'm trying, though, and wbn is helping me through it. I'm trying Griffiths next