3 Answers

I don't think it is a big deal,the baby is finding ways to comfort herself.Will more than likely grow out of it.

It is a form of comfort to babies - I used to do it until I was about 3 yrs old and my Dad put soot on my thumb and yes I sucked it off. Try a dummy not sure where you are in the USA I think it is called a soother (pacifier) not sure - nothing wrong with that - as sucking the thumb can end up by having protruding front teeth which I had "goofy" otherwise no other side effects I think. Quite often Adults do this - I find it a bit affectatious, but there may be other reasons. For babies it is a basic instinct to suck - as pythonlover says they grow out of it..  

my dad told me  if u keep sucking it will fall off