I'm surprised too. I'm also curious about whether the male/female stat is asked directly to the user or is just the gender indicated on the person profile. If it is the second option (I doubt it tho...), I know quite a number of girls that set their profile as "male" for various reasons... It is also indicated that default gender is "male" so maybe a lot of persons didn't wanted to disclose this information and were set up as male (doesn't seems likely either).