It happened to my brother so I don’t think that’s correct
I'm old enough so that when I was growing up, there was no vaccination to protect anyone from getting mumps. If having the mumps really did make ALL males sterile, no matter what, then there wouldn't have been many late BOOMERS nor GEN Xers; if any of them at all.
What I posted is fact and something even kids knew about, as it was once common knowledge.