On Genealogy

I hold to a literal interpretation of the creation story in Genesis 1-2. One support I use for this position is that it seems to me that Jesus, Paul, John and Jude all referred to Adam and Eve or one of their children (Cain, Abel, Seth) in a manner that suggested that they were not figurative, but real people (Matthew 23:35, Luke 3:38, Luke 11:51, Romans 5:14, 1 Timothy 2:13-14, Hebrews 11:4, 12:24, 1 John 3:12, Jude 1:11, 14).

I recognize that there are challenges to address in holding this view. One that crossed my path recently was, "Who did Adam and Eve's children marry?" I would assume the answer would be, "each other". But, then, that leads to the question, "so when did it not become acceptable (spiritually, genetically, or both) for children to marry each other?"