Biologically 2 individuals can't sustain a breeding population. Creationists who claim Adam and Eve were the first and only 2 people created by God and everyone came from them get around this by saying they were perfect archetypes with pure genes or some tripe like that. Others believe more were created (Cain and Ables' wives and such). The sons of Heaven bred with the daughers of Eve introduced more genetic stock and created the Nephilim (but these were supposedly all destroyed in the flood, leaving another mess with Noah's small family to repopulate the earth with too little genetic viability). Then theres the Lilim, and Adams children he had from mating with spirits, creating the mazikeen and such, during his 120 year excommunication, and a whole slew of other possibilities depending on what splinter doctrines you believe. Theres might be some stuff at
http://www.pantheon.org/ (or just read a bunch of anime [img]/images/graemlins/smile.gif[/img])