Both my kids are thumb suckers. I worked for a dentist before I got pregnant, so I wanted to have a binky baby. With my daughter, we used a binky. Occasionally, I would see her sucking her thumb, so I would gently pull her thumb out & pop her binky in. Then, when she was almost 5 months old, I had just pulled her thumb out & popped her binky in, when she pulled the binky out & popped her thumb back in. She gave me this look like "I'm sick & tired of you doing that to me mom!" After that, she'd just suck harder on her thumb when she'd see me coming to take it out. She'd also refuse to open her mouth when I would try to give her the binky. From that moment on, she was a thumb sucker. She also sucks both thumbs (not at the same time). She doesn't care which one. She just turned 6 & we've been trying to get her to stop for 3 years now. Every time she decides that she wants to stop, something happens. Last time, she got the flu & was so miserable that I didn't have the heart to put that horribly yucky stuff on her thumbs. We're still working on getting her to stop, but it is a long, slow process. She'll stop when she's ready. We've even said that we'd go to Disneyland once she has stopped sucking her thumb. This so far has had the biggest influence, since she really wants to go! There may be hope yet! Although, I sucked mine until I was 7 & my husband sucked his until he was 8. I REALLY think there must be a yet-undiscovered thumb sucking gene out there!
My son was about 3 months when he had had enough of the binky & only wanted his thumb. He only sucks his left thumb, and now he usually only sucks his when he's tired, or when he has his lovey. He's 2 now, and I think that in the next year he'll stop. He's not as much as a zealous sucker as my daughter is.
My kids are very easy going, well-adjusted, well-mannered, smart, and kind. There are a LOT of worse things out there that they could be doing than sucking their thumbs! Besides, it is SO much easier when you don't have to get up 10x a night to put their binkies back in because they find their thumbs on their own!!
My brother used a binky until he was 18 months & had to have braces. (He's adopted so who knows about his genes!) Braces have more to do with the shape of your jaw & heredity than if you suck your thumb or use a binky. I had to have braces BUT it was not because I sucked my thumb. It was because my jaw & mouth were too small for the amount of teeth that I had. It was the same thing BOTH my parents had. They didn't have braces, but have had problems with their jaws and teeth being too crowded.
Good luck & don't worry!
Shellie