Blanche Capel | Oct 1, 2009 | 10+ min read
span.cap { float: left; margin: 0 3px 0 0; padding: 25px 0 25px 0; font-size: 80px; font-family: "Lucida Sans Unicode", "Lucida Grande", sans-serif; } By Blanche Capel Choosing Sex The gonad is an amazingly labile organ where male and female signals vie for dominance in the developing embryo. © Lynn Johnson / National Geographic Image Collection --> Editor's Note: The gender of South African runner Caster Semenya&