None of the things you mention are large enough to account for more than a tiny fraction of this observation. There are only a handful of cases like Ghengis Kha

None of the things you mention are large enough to account for more than a tiny fraction of this observation. There are only a handful of cases like Ghengis Khan and that Irish king who are ancestors to a fraction of a percent of the human population, which in any case don't exclude other men from ancestry. If you have ten children and I have one, I am still an ancestor, although your DNA will show up more frequently in future generations than mine. These results suggest the actual exclusion of 95% of the male population from reproduction. Chromosomal disorders affect less than 1% of the population, which would be deep in the noise in this study. With regard to the rate of evolution on the Y chromosome, I think it's pretty plausible that people who do this stuff for a living are aware of it and corrected for it. We don't know that for certain, but since we don't know anything with certainty--only with an overwhelmingly high degree of plausibility--that isn't a big criticism. Edit: also, any harem-keeping species is likely to have a high proportion of genetic losers amongst the males: https://en.wikipedia.org/wiki/Harem_%28zoology%29#Mammals https://en.wikipedia.org/wiki/Harem_%28zoology%29#Mammals