Yes gay and lesbian couples do have sex. Maybe I am wrong but I am assuming that you are asking what do gay and lesbian couples do when they have sex.

Sex does not just mean having vaginal intercourse with a penis and a vagina present. Sex means a wide variety of things. There are as many different ways of having sex as there are types of couples.

Gay couples might do many of the same things straight couples do: kissing, touching, licking etc.