Actually, in Genesis chapter 1, verse 27, it reads:
So God created man in his own image, in the image of God he created him; male and female he created them.
Then in Genesis chapter 2, verses 21-23, it reads:
21 So the LORD God caused the man to fall into a deep sleep; and while he was sleeping, he took one of the man’s ribs and then closed up the place with flesh.
22 Then the LORD God made a woman from the rib he had taken out of the man, and he brought her to the man.
23 The man said, “This is now bone of my bones and flesh of my flesh; she shall be called ‘woman,’ for she was taken out of man.”
In Genesis 1, God created man and woman together, at the same time, presumably out of dust like he did Adam.
In Genesis 2, It states that God created woman from a rib from Adam's side.
Therefore, one could assume that there were two women created. The first was not mentioned again so it's possible that God was not happy with that first creation.
The second, Eve, was created from Adam's side, a part of Adam. Signifying a joint relationship of togetherness.
So it is possible that both women were responsible creating mankind, not necessarily through incest.
