There are more male nerds then female nerds because autism is 3 to 9 times more common in men then women.
A person with mild autism may have Asperger's Syndrome and are often perceived as an archetypal nerd.
Nerd's have better systemising ability, but poorer empathising ability. It is known that extream Nerds/mildly autistic people (more often male) gravitate to courses that cater for their cognitive profile. This is why Math courses have 3 time more AS people then Arts courses. And it is why Dr. Summers said what he said.