[skohan]

You can't? Have you tried it?

[Majestic121]

I'm not sure how to start trying it. I can move my nostrils a bit, but it's more to expand them : I don't have any muscle 'plugging' them it seems

Or are you supposed to plug from the inside, with your tongue blocking the top of the mouth kind of ?

[checkyoursudo]

I don’t know about others but I don’t use my tongue. I can block my nasal passage and breathe through my mouth. I can have my mouth wide open and do this. It must be controlled by some muscle but I don’t know what.

[robofanatic]

you can either breath through nose or mouth not simultaneously. I thought this is normal ..

[checkyoursudo]

I am pretty sure I am breathing through both right now (trying on purpose to do so). I can definitely feel the breath on my tongue and hold something to my nose and smell it.

Whether air from both places actually goes into my lungs? That, I don't know. So you may be right in that regard? I really don't know. :)

[FartyMcFarter]

Are you sure about that? I don't think that's true, not for everyone at least.

[sudosysgen]

I can breathe through the nose, the mouth, and also through both at the same time.

[robofanatic]

"both at the same time" blew my mind!

[warent]

For me this is the norm. I can breathe through my nose, or my nose+mouth at the same time. There is no "just breathing through mouth"