In a high school class, a student asked a priest about the Adam And Eve situation ... having only sons ... How did those sons procreate?
The delayed answer involved Eve ... and some laughs.
It’s very clear that the sons of Adam procreated with the daughters of Adam - but that was long before the human genome had been degraded to the point of where it is today. It wasn’t long after that - and after the flood, that close inbreeding was forbidden, and for good reason.
What was an absolute necessity in the beginning, was later to be absolutely forbidden.
Bible says he found his wife in the land of Nod!