A paternal bond is the human bond between a father and his child. Father-infant bonding Infants can become attached to their fathers. Mother-infant bonding has been a common focus in household research; however, more studies in the United States and Europe have been focused on the details of father-children attachments. In the book, Gender in cross-cultural perspective, Barry S. Hewlett showed that infants do create bonds with their fathers. She explained how recently born children bond with their fathers at similar ages during development. Researchers question how father-infant bonding occurs because fatherhood has many different roles in various cultures. Questions arise about how fathers have the ability to bond with children if they do not have the same kind of role that mothers do in the baby's development. The father of a child can develop the bond during the pregnancy of his partner, feeling attachment to the developing child. Research indicates that this may have some biological basis. Statistics show that fathers' levels of testosterone tend to decline several months before the birth of the child. Since high testosterone levels are linked to more aggressive behaviour, low levels may enhance the ability to develop a new relationship bond. Fathers also have an important bonding role after the child is born. Fathers find many ways to strengthen the father-child bond with their children, such as soothing, consoling, feeding (expressed breast milk, infant formula, or baby food), changing diapers, bathing, dressing, playing, and cuddling. Carrying the infant in a sling or backpack or pushing them in a baby transport can build the bond, as can participating in the baby's bedtime routine. These are broad activities that fathers share to develop their father-infant bond. Fathers also have specific bonding roles that develop from their different cultures and societies. European and American culture European and American fathers are seen to have more of an aggressive and vigorous relationship with their child. This does not mean harmful; however, it means there is physical and highly stimulating interaction between the father and child. This gave the child emotions that reflected an exhilarating and fun-loving experience that allowed them to create a father-infant bond different from a mother-infant bond. It is shown that an infant's facial expressions and emotions towards their father is significantly different from their emotions towards their mothers, even at a very young age. This shows that a father being present gives the child