Interestingly, I also had braces. But I suck my thumb more often now (still seldom, but more often than it used to be) than I did when I was a teenager. It could be that I no longer smoke, and as a diabetic who needs to lose weight I have to watch what I eat, so thumb sucking is the only oral soothing technique that is LEFT. It isn't really a habit. I never catch myself sucking my thumb when I didn't realize I was doing it. I will allow only my husband to see it, and he's OK with it. In fact, he does something similar. When he's winding down after a full day, relaxing in front of the TV, or falling asleep, he puts only the very tip of his thumb between his lips. He's not actually, full-on, sucking his thumb, but from some angles it looks as if he is. And honestly, I think that's kind of cute, especially when he's curled up with his favorite blanket. Reminds me of a middle-aged Linus. Lately I'm wondering if there really is any harm in these things.