Some babies learn the art of sucking from the womb and master it in the first few weeks of their lives on earth or learn to suck as soon as they are born. Sooner or later, the finger sucking becomes a habit which is usually very very hard to break. The only good thing about babies that suck is that they always seem to be at peace and can easily sleep on their own without fussing. This also applies to babies that use pacifiers. The big issue, however is always how to suck and which is the lesser evil, pacifier or thumb.