My sisters mouth always hangs open

Question

My sister isn't retarded and she's really smart but for some reason her mouth always just slightly hangs open. No one elses does and it bothers her because it makes her look retarded. The dentist said she needs braces, could that be the cause of this

Answer 1

It could be a little bit because sometimes your teeth stick out a little bit and it isn't comfortable to relax and close your lips.  She may also have a hard time breathing through her nose.  When I was younger my mom always told me to close my mouth or I was going to catch flies, now I just do it automatically without thinking, but it wasn't natural.  I needed braces and I have small sinuses or something, so I can't breathe really well though my nose (I can, but I feel like for long periods of time I don't get enough oxygen or something).  It could be something else, but it's just something to think about.  With some practice, you learn to keep it shut.  

Answer 2

Maybe she has a little trouble breathing through her nose.  

Answer 3

If she has an overbite that could be what's causing it.