Is it possible to make sims have preference for both female and male clothing?

@MiaBlueMarble

You don't really have to. When you outfit the sim, at the top of the clothing list, you'll see "feminine" or "male". Just click on the little X next to it and you'll see both male and female clothing.

The only clothing you won't see are ones that are tagged as "restricted" to a female or male body.