It was quite common for families in Europe to have 10 surviving children that reached adulthood and got married. To speculate that we have a higher growth rate in the 21st century than there was in the early 20th century and earlier seems speculative. I would posit the opposite, especially considering their was little or no ‘family planning’ back then. So, again, I still don’t see what relevant demographics exist today could account for an age gap issue that was not present for hundreds of years prior.
As far as pogroms, I don’t see any reason to speculate that the antisemites targeted men over women. Same with health problems. Again, from personal family history (on both sides) as well as a general knowledge of Jewish history, having 10 married siblings was not uncommon in the least.