Studies now show a clear relationship between whether an infant was breast-fed and its likelihood of becoming a smoker as an adult. It was found that babies who were largely bottle-fed represent the majority of adult smokers and the heaviest smokers, while the longer a baby was breast-fed, the less chance there was that it would become a smoker. It seems that breast-fed babies receive comfort and bonding from the breast that is unattainable from a bottle, the consequence being that the bottle-fed babies, as adults, continue the search for comfort by sucking things. Smokers use their cigarettes for the same reason as the child who sucks his blanket or thumb.