This question has baffled me for a long time. Do we all come from incest? Isn't incest a sin?
Leviticus 18:6-18
6 " 'No one is to approach any close relative to have sexual relations. I am the LORD. 7 " 'Do not dishonor your father by having sexual relations with your mother. She is your mother; do not have relations with her. 8 " 'Do not have sexual relations with your father's wife; that would dishonor your father. 9 " 'Do not have sexual relations with your sister, either your father's daughter or your mother's daughter, whether she was born in the same home or elsewhere. 10 " 'Do not have sexual relations with your son's daughter or your daughter's daughter; that would dishonor you. 11 " 'Do not have sexual relations with the daughter of your father's wife, born to your father; she is your sister. 12 " 'Do not have sexual relations with your father's sister; she is your father's close relative. 13 " 'Do not have sexual relations with your mother's sister, because she is your mother's close relative. 14 " 'Do not dishonor your father's brother by approaching his wife to have sexual relations; she is your aunt. 15 " 'Do not have sexual relations with your daughter-in-law. She is your son's wife; do not have relations with her. 16 " 'Do not have sexual relations with your brother's wife; that would dishonor your brother. 17 " 'Do not have sexual relations with both a woman and her daughter. Do not have sexual relations with either her son's daughter or her daughter's daughter; they are her close relatives. That is wickedness. 18 " 'Do not take your wife's sister as a rival wife and have sexual relations with her while your wife is living.