Threshold is a roleplaying environment, and one of the fun things about a fantasy roleplay environment is you can be something totally different than what you are in real life. On occasion, this might include the sex of your character. This is totally allowed here, but there are some guidelines on such a choice that will ensure that all people involved in the roleplaying are treated fairly. If you are playing a character of the opposite sex of your real life self, you MUST tell the people you roleplay with regularly of this fact. This is ESPECIALLY true if your character flirts, mudsexes, or engages in other such activity.
If you are a gender bender, you're probably screaming: NO FAIR! Well, let's talk about fairness. Is it fair that the gender bender gets to have all the knowledge about the situation, but the other person does not? Is it fair that the gender bender takes advantage of the general assumption that people play their real life gender in order to get someone to roleplay with them, even though they might not want to if they knew the gender bender's real sex?
This boils down to the fact that people should be able to decide who they want to play with. This is especially true for things a little more emotionally charged like IC relationships. For these reasons, if you want to gender bend, then you need to be honest (out of character) to the people with whom you roleplay.
If you wish, you may use the describe command to add to your OOC that you are a gender bender.