Ukisoma "The book of Adam and Eve" (Hakipo kwenye biblia ya kawaida),Utakuta mistari hii hapa chini.
2 And thereafter, Cain slew Abel, but Adam was then one hundred and thirty years old, but Abel was slain when he was one hundred and twenty-two years. And thereafter Adam knew his wife and he begat a son and called his name Seth.
xxiv 1 And Adam said to Eve, 'Behold, I have begotten a son, in place of Abel, whom Cain slew.'
2 And after Adam had begotten Seth, he lived eight hundred years and begat thirty sons and thirty daughters; in all sixty-three children. And they were increased over the face of the earth in their nations.
Hapo utaona Adam alizaa watoto 63 jumla wakike 30 na wakiume 33,walioana wao kwa kwao na kuzaliana.So kuna uwezekano mkubwa pia Cain alimuoa moja ya dada zake pia.