Cain was married to either his sister or his niece. Sarah was Abraham's half-sister. Abraham's brother Nahor married his niece Milcah. Why was incest allowed in the Bible?
Why was incest allowed in the Bible?
The Bible doesn't say, but we can speculate. Adam and Eve were created genetically pure. They had no congenital defects to pass on to their offspring. DNA damage accumulates over time, but even 2000 years later, when Abraham was born, genes were healthy enough to allow for him to marry his half-sister. Genetic abnormalities did not influence marriage partners until they had multiplied enough to be a health risk.
Another possible reason is the patriarchy and tribalism common at the time. When Isaac needed a wife, Abraham did not want him to marry one of the local Canaanite women. Their religion was anathema to the worship of God. So he sent his servant back to his homeland to find a woman from his relatives (Genesis 24). Later, Rebekah convinced Isaac to send their son Jacob away to her family to find a wife (Genesis 27:46). In doing so, the family unit was kept strong, and ungodly religious influences were kept to a minimum. This was particularly true among Egyptian royalty, where incest was used to maintain the royal line—and make for some very unhealthy pharaohs.
God tightened incest standards when He gave the law to Moses. A man could not marry his mother, step-mother, mother-in-law, aunt, father's brothers' wife, sister, half-sister, the sister of his living wife, stepdaughter, daughter-in-law, granddaughter, or step-granddaughter. Basically, he could not marry anyone descended from him, anyone who would cause problems with his wife, or anyone directly connected to the older men of his line. It is thought that there was no mention of a man marrying his daughter because the disgrace of the relationship was obvious (Genesis 2:24 may also indicate that marriage between children and parents had never been considered allowable); but a man could marry his niece. A woman could not marry her grandmother's spouse, step-father, father-in-law, brother, half-brother, living husband's brother, nephew, brother-in-law's child, son, stepson, or son-in-law. A woman could marry her uncle.
In ancient times, it was often taboo to have relations with your child or sibling, but the first comprehensive mandate in the Bible didn't arrive until the Mosaic Law. In the early Old Testament, incest was allowed because it wasn't genetically dangerous and it wasn't against the law.
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