Yeah, the default parameters are female, Cuff, since that's what they model. We call the default avatar "Ruth".
While it'd be nice if the Lindens had five or six "default" avatar body settings to choose from, as sort of a way to immediately demonstrate to new users the full range of our ability to deform the avatar mesh... we don't have that, so you have to play around wiht the avatar sliders until you find something that works. Most people refine their avatar over a long period of time. Mine's just an updated version of the same one I initially created 14 months ago.
As Cienna says, the sex toggle doesn't actually do anything except make some sliders available and others inavailable, depending on which setting you picked.
Some time ago, a few of us suggested that -- much as the new "sitting" animation for women is completely insane -- it was a little silly to restrict access in that way and that we supported an "all sliders" toggle in addition to the present two. Responses ranged from supportive, ("hey, yeah, that's a good idea"

to confused, ("Er, what exactly do you
need that for?"

to vehemently opposed. ("It's not natural!" --Right, like purple skin and GG-cup breasts on an 8-foot-tall woman are?

)
Personally, I'm for anything that allows me greater freedom in making my avatar look and move... well, like a normal person, but the current trend seems to be in the opposite direction. Come version 1.3, I expect those of us with the "female" toggle turned on will simply be unable to wear trousers altogether, and will mince around, stopping before we sit to place a doily down to protect our petticoats.
