So I have some kid characters I've been working with, and some of them have this issue with their mouths I can't figure out and can't find answers to here or on Google. 

Their mouths are pinched weirdly (widen mouth" just makes it worse) and when they smile, there are weird black marks on the sides of their mouths. Here's a couple screenshots:





No matter what I do, I can't get the mouth to look right. I used the baby avatar and "aged" it to get the kids, so I can't imagine it's an issue with them being kids... why ideas? Thank you!