That theory may be true in some cases, but I know plenty of female friends who are anything but masculine and are certainly quite orgasmic.
From personal experience, I am very large breasted, fair, small boned and feminine to the max, but honey, with the right man I'm a steam engine. There may be some truth to the idea that the more masculine women are more orgasmic than their less testosterone laden sisters, but there are planty of estrogen babes who can set the firecrackers off with the best of 'em.
More than Science written in stone, the idea that the masculine chicks are more sexually responsive than pretty feminine ones sounds like wishful thinking on someone's part. Bubt that's just my opinion.....