By sensitive to interbreeding do you mean that's the reason why humans can't have offspring with other apes? Curious to know how this is implied by a genomic bottleneck.
I think they meant incest. If we already did our share of it in the distant past, then fun with your cousin leads to a baby with a pig's tail. Or at least it did for the Buendía family: https://en.wikipedia.org/wiki/One_Hundred_Years_of_Solitude