I was once confused about Gilligan’s Island. But no more, thanks to this explanation.
Well, sure, but look at the 7 stranded castaways there on Gilligan’s Isle. (yeah, God is gonna get me for that)
There were not really any uber-Alphas trying to run the show. They were pretty nice screw-ups and misfits, actually. Even Thurston and Lovey had their moments.
Kind of the group I’d love to have over for a BBQ sometime. 
Sure, until Gilligan knocks over your lawn mower gas can onto the hot coals, infuriating the gorilla.
OK, I yield.
Wait, did anybody address the mathematics and genetics if we assume that Lovey is still fertile?
No, because she couldn’t have been a day under 45. (Natalie Schafer, the actress who portrayed her, was in her sixties at the time.) And three women instead of two doesn’t make a lot of difference anyway. Somewhat more genetic diversity but you still run into everyone being cousins or double cousins by the fourth generation.
True. He must’ve replaced every nail with the new glue. Not really that smart, IMO.
Is there some reason why everyone in this thread is assuming that gay = infertile? Whatever the proclivities of the Professor, he is still available breeding stock for the purposes of the question.
The really funny part is that this explanation actually does makes sense of the situation.
Sure, until Gilligan hits him in the 'nads with a coconut.
Infuriating the gorilla, no doubt.
The Professor:
Wait, the Professor was Batman!? No wonder he always seemed so prepared!
That works so many ways.