Dave T hit a home run!! All you reveal about yourself in sex is gender and basic or advanced knowledge of the act, and if things go wrong, they can be rationalized away. BUT when you talk everything you say AND everything you leave unsaid reveals tons about YOU as an individual. And for some people self revelation is the last thing in the world they want. (The reasons for want to hide their true selves can be many and complex, and could be a whole new thread in itself.)

Lyle