But Cain Did It…?By Rabbi Jack Abramowitz
Anyone who curses a parent is liable to the penalty of stoning. In the case of adultery, both the man and the woman are liable to the death penalty. (The default form of execution, when it’s not otherwise specified, is strangulation.) Relations with a stepmother or a daughter-in-law incur stoning for both participants. (Remember, these are consensual acts.)
The penalty for homosexual intercourse is stoning and the penalty for marrying a mother/daughter team is burning. (In such a case, only the second wife is liable to punishment, as the first woman acted permissibly.) If a man or a woman commits bestiality, both the person and the animal must be executed.
If a man has sex with his sister, even only a half-sister, they incur kareis. This relationship was only permitted to the children of Adam because their siblings were the only potential spouses in the world (see Talmud Sanhedrin 58b). Relations with a woman who hasn’t used the mikvah following her period also carries the penalty of kareis. Sex with an aunt will cause the participants to die childless. (This punishment is called “ariri” in Hebrew.)