Nine days after they first mated (humans had a much-accelerated, painless gestating period in the Garden of Eden), Eve gave birth to the first human child. Her name was Cate, and like Ashley, her skin was dark, but like Eve, she was born with a vagina. Cate's parents were surprised by her mix of their bodies, but of course loved her very much.
Ashley and Eve were very curious about breeding, though, and wanted to bear another child. So while Cate was happy on her own one day, they found a secluded place and mated again. In nine days, Eve bore their second child. They named her Abby, and Abby was fair-skinned like Eve, but like Ashley, she had a penis. So it became clear to Ashley and Eve that when they mated, human offspring could share either of their skin tones or reproductive organs, and the chances were about even of each.
Cate and Abby grew healthily, and in time their bodies matured like their mothers'. They both grew breasts and their reproductive organs gained functionality. But once they were old enough to mate, something would happen that finally ruined the Creator's until-then perfect plans...