Just for perspective: I am a man in my mid-40s and for as long as i can remember i had this question… is it normal that i can shut my nose close just with some muscles?
I always wondered why some people hold their nose shut with their fingers while jumping into a pool or when exposed to some horrible smell… i never had this need. Changing my sons diapers? No problem! Cleaning the latrines while in the army? Just a breeze!
Ehm… yeah… just thought about this…
No but I can close the air duct just above my soft palate (not really sure what that part is called), so effectively I can’t breathe through my nose but if I were to go underwater water would still get in, if that makes any sense. I’m not sure if this is common. I know that that part is supposed to close automatically while swallowing to prevent food from going up in the nasal cavity, but idk how common it is to be able to control it separately. It’s handy to avoid smells without using my hands though :)
I can do that as well, so at least you aren’t alone!