Why not? No more difference than doing a roommate or dorm mate in college. After all, they are NOT related.
BTW, I guess AEv step-brother is not hot.
BTW2, different societies have different "rules" on all that.
Caesar, this is not proper.
CAESAR (recovering his self-possession):
Pardon him, Theodotus; he is a barbarian, and thinks that the customs of his tribe and island are the laws of nature.
Caesar and Cleopatra, Act II -- [George Bernard Shaw]