What’s the most common thing nearly half of American toddlers do when they’re tired, relaxing, sleeping or being scolded? They suck their thumbs! Thumb-sucking is the earliest and most common habit among children. It’s nothing for parents to worry about—unless the habit persists. Only after age four does thumb-sucking threaten to damage children’s teeth Some thumb-suckers simply rest the thumb in the mouth, sucking only at certain times. Others work [...]