Where in the Bible does it say that Adam and Eve had 800 year of life? Where in the Bible does it say they had many kids? What the Bible DOES say is that their children produced 2 lines of descent. One is the Cain line which was in ongoing rebellion against the will of God, and the other was the Seth line that lived in obedience to God. And the Bible for sure says NOTHING about lack of incest genetic problems because of the purity of their genetics. It is so easy to say that the Bible could never be wrong in the light of more recent knowledge. It is so easy to come up with Biblical answers that are NOT in the Bible to “prove” anything you want to prove. There may be people in science with egos that stick to wrong answers, but plenty of others in science are there to point out their mistakes and generally be believed with enough evidence.
The following verses trace the genealogy of Seth, just one of Adam's sons:
Gen 5:3 And Adam lived one hundred and thirty years, and begot a son in his own likeness, after his image, and named him Seth.
It doesn't mention it here but we know before this there were at LEAST two other kids, Cain and Abel. And likely many more. Remember the Lord had instructed them to "go forth and multiply". Adam and Eve were likely the most fertile people ever. Created by God himself to go forth and multiply.
Gen 5:4 After he begot Seth, the days of Adam were eight hundred years; and he had sons and daughters.
So Adam lived for 800 more years AFTER Seth and MORE sons and daughters.
Gen 5:5 So all the days that Adam lived were nine hundred and thirty years; and he died.
So Adam lived 930 years. Assuming that there was a certain amount of time to mature it's going to be about 900 years of having kids.
What the Bible DOES say is that their children produced 2 lines of descent. One is the Cain line which was in ongoing rebellion against the will of God, and the other was the Seth line that lived in obedience to God.
And all those other sons and daughters that Adam and Eve were also lines.
And the Bible for sure says NOTHING about lack of incest genetic problems because of the purity of their genetics.
When God created man he said it was "very good". To me that signifies perfect genetics. Perfect DNA. Or at least what constituted very good in God's eyes. They were the best God could make for what he intended.
To NOT believe that Adam and Eve had more kids then just 3 is being willfully ignorant of scripture. Looking for non-biblical answers when a good case can be made from the bible isn't profitable either.