The WT has often alluded that there is a genetic defect in humankind ever since Adam and Eve ate of the "forbidden fruit." We've all heard the "dent in a pan = dent in the cakes" illustration countless times over by the Society and, for that matter, by a number of fundamentalist Christians. But, there is an enormous problem with this line of reasoning.
Sex cells (gametes) of males are constantly produced from the time of puberty practically till the day men die. The production of gametes in females, however, is not constant. In fact, females have all the gametes they will ever produce already in their bodies at birth. There is absolutely no production of sex cells -- which is 1/2 of all the genetic material available to their offspring -- during adulthood.
Eve -- a mythical character in my book, but a real flesh-and-blood woman for the JWs -- would have had all her gametes in her body before she ever sinned and ate the curiously unknown fruit. This would mean that her genetic contribution to her offspring would have been sinless and perfect. Since the JWs believe (unbelievably!) that a perfect genetic contribution "overpowers" imperfect genetic contribution (think Mary the mother of Jesus) all of Adam and Eve's offspring would have been perfect, thus the idea of a genetic basis for sin is demolished.
Oh, I guess a clever JW will work their way around this obvious problem (probably no JW would link the above into a question, though) by saying that there was a "special condition" in Eve's case -- that either God didn't give her gametes till after she sinned or that God "zapped" her gametes and genetically altered them to be imperfect. Such reasoning just illustrates the absolute lunacy of the original doctrine and the great lengths one must go to to make the Eden myth fit the modern world.
It was so much simpler for Christianity before the scientific method!