How did Kane get his wife if his brother and his parents where the only ones on earth?

Answer 1

Cain and Abel are the only two that were mentioned at that time, but they could have literally had hundreds of sibling. In the genealogy of Adam in ch. 5 of Genesis only Seth is mentioned, and Adam was 130 years old when Seth was born, and Adam is said to have lived another 800 year after that and it says he begot sons and daughters. We only know about Cain and Abel because of the story in ch. 4 and no other names are mentioned. I personally think that Cain was a head of a clan at the time he killed Abel and went into an exile. In ch.4:17 it is said that Cain had a son named Enoch and he built a city and named the city Enoch after his son (firstborn in exile I assume).

One thing you need to remember, is that back in those day people lived close to a millennium and where generally very healthy, so there would have been a population explosion in the first few hundred years.