That is something atheists and assorted Bible-rejecters cannot answer in scientific terms. Without intelligent design at the beginning DNA would have never become the essential part of life on earth that it is. But God-rejecters have no scientific clue where the intelligent design came from which created DNA. Francis Crick was awarded a Nobel Prize for his research into DNA, and he suggested DNA came to earth on spaceships piloted by aliens. I guess Crick refused to believe God designed and created life on earth just like the Bible says.