After he begot Seth, the days of Adam were eight hundred years; and he had sons and daughters (GENESIS 5:4).
Adam and Eve had many children. Adam lived to be 930 years old, and Jewish tradition states that he had 33 sons and 23 daughters. (That is a really big family!)
Most people believe that Cain married his sister or his niece, and the Bible does not tell us what her name was. Keep in mind that way back then (about 6,000 years ago) close relatives could marry — they had to in order to start their own families. Even Abraham married his half-sister. Of course, we can’t do that anymore because of the effects of sin on our bodies and because God told Moses that people were not to marry close relatives from that time on. Now when we marry, we marry someone not so closely related to us.
While we’re speaking about marriage, Calista, remember that according to God, marriage is one man and one woman until death — that’s how God commands it.