>>590428Humanity was spawned by only two people, Cain's wife was his sister or niece.
I don't think incest is "biologically programmed" out of us, it's purely cultural, and of course men can restrain themselves.
For example this scene in: Die Antwood - Baby's on Fire
https://youtu.be/HcXNPI-IPPMOf course incest was deemed wrong later, however different types of incest are treated differently. According to Leviticus 20, incest with your sister was punished less harshly than other forms, only requiring you to be exiled out of Hebrew territory.