i saw this and thought "what a lovely opportunity to spew my knowledge on a topic i'm obsessed with!" that said, apologies in advance for length...
the sun sign represents a person's ego. self-esteem, and the most effective methods of self expression. just as the sun is the center of the solar system, so the sun sign represents the core & basic you-ness. it has very little to do with sexual appetite, openness, or communicative tendencies.
if you're looking for those qualities, the best place to look is the mars sign, and in 2nd place is venus sign. these two signs have more of a role in sexual expression, especially when they aspect each other (i warned you i was gonna get geeked out, but u asked for it...)
aspected venus and mars signs amplifies the sexual appetites. a mars in scorpio or taurus are said to be more passionate sexually, etc. another thing to think about (since i'm guessing not too many ppl will look into it fully) is that the venus sign can only be 2 signs ahead, 2 signs below, or the same as your sun sign. so there's a 1 in 5 chance that your venus sign is the same as your sun sign. if you wanna assume that your venus is the same as your sun, feel free--although there are several sites that will tell you all your planet placements for free. u can get the houses too if u kno your birthtime. google "natal chart" or use
Horoscope and Astrology - Homepage - Astrodienst.
my venus (planet of sensuality & love) happens to be virgo, just like my sun. however, my mars (planet of action and sexuality) sign is in gemini. they form a negative aspect: square. this aspect, as far as sex goes, gives me stamina and strong responses. however, i don't dirty talk bcuz it makes me feel embarrassed/awkward (virgo trait) even tho i'm great at writing erotica & i rock at witty & sexual flirting so i kno i have the words (gemini trait). i get off on feeling like i'm pleasing my man, and i find it sexy and in a way, powerful to do wat he wants me to (virgo is the sign of service). mental stimulation and foreplay is very effective, bcuz good sex comes from between the ears, almost exclusively. a seductive man with a golden tongue could easily charm me out of my panties (gemini mars)... if i were willing to be easy--and i'm not. just doesn't feel right (virgo chastity again).
So basically, i have a ton of martian sexuality in the attic of my mind because i have a virgo sun & venus tag teaming to keep it locked away out of fear. BUT, i have noticed that certain people, usually ppl who i feel more comfortable with myself & playful around, have a better shot at tapping in. the buried treasure chest does indeed seem to have a key, it's just that not any ole man can find it. the Average Joe gets a demure but willing & sensual partner, the Virgo side. I wll feign innocence, serve my lover like a king, and do almost anything he asks me to as long as it isn't TOO raunchy, and i will not do anal, EVER. i have values, prioritized, and all but listed. i will express my love, through sex, like a Virgo. but my desires & carnal instinct want dirty talk and roleplay and spontaneity and intellectual talent, not to mention anything oral...

That's the hidden Gemini for ya.