Brain size and male/female membership ratios in IQ societies I belong to two high IQ societies one of which is Mensa. The gender breakdown at Mensa is about sixty five percent male to 35 percent female. I posted an opinion that the gap is due to larger brain size in males. I was immediately attacked by several suffrage queens who told me I was full of it and then called me names that are best left in the gutter. I do however, believe that brain size plays a decisive role particularly in the higher regions of intelligence testing. This applies only in a broad sense and not in all circumstances so please do throw up a bunch of examples of stupid people with large heads.Please Register or Log in to view the hidden image!