All five of the kittens we got on March 28 are boys. All of them. And A couple of them started genital nursing before we caught it and separated them to prevent it continuing.
The littlest one (who was actually the noisemaker who got them all found in the first place) got affected the most and when I got my doctor to look at him a couple of days ago he was in fact constricted if not blocked. Conveniently I work at a cat only practice under a very experience and highly qualified doctor, and we got a LOT of urine out for a kitten this small.
Apparently hes recovered quite nicely as he relieved himself on me while I was watching TV after work. Enough that I am no longer concerned about that particular problem.
He also had an eye completely swollen shut with an infection, but Terramycin cleared that up just fine. We have only had him for 9 days and hes already visibly bigger than he looks in this picture.