The Bible claims that Adam and Eve were the first humans and that three of Adam's sons were named Cain, Abel, and Seth. In the first recorded murder, Cain killed Abel. Since these were the first people on earth, this question is often asked, “Where did Cain find a wife?” This question puzzles most people, not because the answer is complicated, but because they have been trained to think based on evolutionary assumptions.
Evolution begins with the assumption that nature has always functioned similar to how it is operating today. Evolution also teaches that things are increasing in complexity and improving over time. The Bible teaches the opposite–Adam and Eve as originally created would have been perfect with no genetic mistakes in their DNA. Genetic mistakes started to occur after the Fall and have quite rapidly built up over time. Today, whenever both parents have the same genetic mistake, their children develop the resulting genetic problem. This is why brothers and sisters cannot marry. It was mankind's disobedience that brought this imperfection into God's creation.
The biblical law against brothers and sisters intermarrying did not exist until 2,000 years after creation (approximately 4,000 years ago). Abraham (alive approximately 3,000 years ago) was married to his half sister. The Bible states that Adam and Eve had other sons and daughters [Genesis 5:4]. Jewish tradition even suggests that they had 46 children. Cain merely married one of his sisters.
From A Closer Look at the Evidence by Kleiss, August 4.
