Is Thumb Sucking Hereditary?

Eli has been a thumb sucker since he was about two months old. See below- so sweet...
At about 18 months, I think Stephen and I both began to wonder, "When will he stop sucking his thumb?" I talked with his pediatrician about it and read articles about thumb sucking, and from what I understand, we should not try to make him stop sucking his thumb. It makes him feel secure, and most of the time, he probably doesn't even realize he's doing it. At two, he is still my little thumb sucker.
He looks so cute when he sucks his thumb, and in a way, it makes him still seem like a little baby, but I really do wish he would stop doing it. I'm not going to go out and buy an anti-thumb sucking device or put hot sauce on his thumb, (He would probably just suck the hot sauce off anyway. He seems to like it when Uncle James give him a taste of his Tobasco) but I really hope he breaks the habit soon.

Eli, being the thumbsucker he is, has felt the need to try to make Bella "suck the thumb," too. Since Bella's birth, there have been times when Eli has said to her, "Suck the thumb, Bella," or "Bella, put the thumb in the mouth." He has tried putting his thumb in her mouth, and once, he even grabbed her hand and tried putting her thumb in her mouth.

I have caught Bella with her thumb in her mouth a few times. Usually, she's kind of chewing on it. I have seen her suck on it a few times, but she does this with her fingers sometimes, too.

See, nothing major, just a little thumb gnawing going on... until tonight! Tonight, Mom rocked her to sleep, placed her gently in her crib, walked out of her room, and announced to me that Bella was sucking her thumb. She wanted me to go look. As I tip-toed into her room, I expected to see my sweet baby girl lying there in bed with her thumb half-way in her mouth, resting on the side of her face. Is that what I saw? No! Bella-boo (That's what I call her sometimes) had full blown thumb sucking action going on.


I, of course, had to snap a picture. When I did and the bright flash illuminated her room, it kind of startled her. She really started sucking then! The sweet sound... She sounded just like Eli when Eli is going to sleep- suck, suck, suck, stop, suck, suck... The sound of a baby's cries and coos change as they get older, but the one thing that doesn't change is the sweet sound of a precious little thumb sucker.