Me too. Although I thought what he was going to say is the limited genepool would make grandchildren impossible (well nearly...) and generations after that impossible.

People are asking for citations to actual literature that support your claim that a pair of fertile people can't reproduce. I think what you're actually saying is that you can't bootstrap a viable population from a pair of people (which is definitely true from a population bottleneck point of view), but I think you're massively overstating your case. It would really help if you could point to some modern well-accepted textbook or paper that supports your claim.