Is this some kind of talk being spread around in congregations? The funny thing is that a while ago someone tried to make the same argument, saying they could disprove evolution because no one can explain how we evolved male and female at the same time. Not much later than that, a friend of mine (a JW) told me the same thing. I thought either he read the same post or this is going around the congregations as a means to challenge evolution. I know my friend and I know he does not come around this website.
By the way, not even the sperm in your own testicles are all the same. Much less compared to your father's