Indeed, they did, since Cain was Able; as it is written:

And Adam knew Eve his wife; and she conceived, and bare Cain, and said, I have gotten a man from יהוה [who is Elohim, the Lord]. And she again bare his brother Abel. - Genesis 4: 1, 2

"And the sons [Cain and Abel] of [Eve with] Elohim saw [their sisters] the daughters of Adam were fair and they took them wives of all which they chose" - Genesis 6: 2