My lips look crooked when I smile, is this a muscle issue? (Photos)

I don't feel like my smile always looked like this growing up. But my smile is very crooked. When I smile, the right side lips crease over, so they "disappear" more than the left side. The left side looks fuller when I smile. It makes my face look asymmetrical. When I'm not smiling, it doesn't look asymmetrical in my eyes. But when I open my mouth, you can see the asymmetry too. Is this a muscle issue? What can I do about this issue?