Gender
In all Sims games, there are male and female Sims, but except for their appearance, the differences between them are minor. The most prominent difference is that one male Sim and one female Sim are required to create a baby through in-game interactions. Also, gender-specific pronouns will often be used when describing the Sim in a pop-up or on a tag, such as those which can appear for some jobs and moods.
As in real life, male and female Sims can clearly be distinguished by their appearance. Basically, females will look more feminine, have breasts and lower muscle tone, and males will look more masculine, lack breasts and have higher muscle tone. They also develop different voices in every life stage after child. These features are purely cosmetic and have no effect in the game.
In The Sims 2 and The Sims 3, there will be some customization features in CAS that are only available to one gender. For example, only male Sims will have options for facial hair.
While using the toilet, a male Sim will stand up in front of it if his bladder is still high enough. When a female Sim takes a shower, the game, if unmodded, will censor her breasts.
In The Sims: House Party, The Sims: Hot Date, and The Sims 2, there are doors that are used exclusively by one sex, usually used for washrooms on community lots.
With the new pregnancy feature in The Sims 2, females can get pregnant through woohoo and males can get pregnant through alien abduction.
In The Sims 3, certain relationship labels are organized by gender.
