What causes lip incompetence

[JeanneDArcAlter]

Example

I am not referring to when the lips actually arent touching each other but when they have the appearance of not doing so from the side
It seems this is totally random and you cant control it

 

[JeanneDArcAlter]

@thecel

 

[JeanneDArcAlter]

I think this is caused by protrusive/non caucasian lips

 

[first snow]

bones.

 

[IwillRope2024]

open bite or overbite

i have it too