Ever wondered

Genesis 5:4 tells us that Adam and Eve 'begat sons and daughters.' Josephus, the Jewish historian, states that 'The number of Adam's children was thirty-three sons and twenty-three daughters.' The point, of course, is that Adam and Eve did have a great many children. Brothers must have married sisters at the beginning. The law against close intermarriage was not given until the time of Moses. That's the only logical way the world could have been populated with just one couple.

Bible cannot give you an answer to this question, but Science can.

From my Biblical perspective... They bore more than just Cain and Abel, in fact they had several dozen children. Cain and Abel are only the most well known. There's also the possibility that God created more humans than just Adam and Eve. Genesis says that Cain left the land of his family to travel to Nod and there found a wife who he had children with. Where'd he find that wife? Well, it could have been one of his sisters or it could have been a woman from a whole new tribe of people created after the fall.

I wasn´t told that when I was little. I was told the Bible said that "there were Adam and Eve who bore Cain and Abel". But my parents did not consider the Bible a Holy book so I didn´t either. In fact, I doubt that my parents ever read it. I have read most of the Bible though and think it is very interesting. But I don´t believe it was written by God, I don´t even think it´s the story of humankind but of the jewish, as told by wise jewish men.