text: Whether you believe in Adam or Eve or that man descended from some primitive Ape-like man, at some point there had to be incest.  Mankind has 46 chromosomes.  Apes have 48.  If mankind resulted from a genetic mutation, there still had to be incest within the first few individuals in order to propogate this mutation.\nIncest is only wrong in that it can cause mutations which are recessive to be displayed.  Incest is therefore forbidden in order to prevent birth defects and aberrations.