First of all any, reference to Eve must depend upon Biblical exposition; that is, Adam and her were created on the 6th day. As the only two people in the then-world and with immediate responsibilities, we can safely presume God created them as adults, perfect adults. For instance, as a 25 yo adult she might have been only five minutes old.
If Eve was created from Adam's rib, that would mean that they were related and Cain and Abel were products of incest.
not only that, which means we're all cloned from clones. but also the fact that neither adam nor eve had belly buttons. the rest of us do.
And who did Cain and Abel marry? And Enoch the 3rd son, after one had already been killed built a city before he had any kids....where did all the people come from to populate this "city".
Referring back to the "incest" issue - remember that Adam and Eve, and their immediate descendants, lived for hundreds of years. Remember - genetically perfect; ideal environment. They would have had ample time to produce lots of offspring.....and their offspring. Play with "what if" math, and it's easy to see how this works out. And just because Genesis doesn't mention other offspring, doesn't mean they didn't exist. In fact, this very question suggests that there were many other children.
