User blog comment:Saturn120/What if Karl Marx Was Never Born?/@comment-32656-20140512075716/@comment-4621372-20140515205038

A few 1000 will make it to the egg. This is less than one percent of the original number, but is still sizable enough that the chance of a single particular cell making it there is TINY.

Furthermore, minor differences, in, umm, the flow of the bodily fluids, might cause Hitler's cell to go down different paths.