Hands-on fathers who cuddle and play with babies early in life develop a stronger bond with them, experts say.
Hormones which are crucial in developing a mother-child bond are also present in men, a new study has discovered.
Oxytocin, known as the "cuddle hormone", increases empathy and motivation to care for a child, and helps synchronise a father's emotions with that of his children.
The hormone is released by mothers while they breastfeed and cuddle their babies. But experts have now realised it surges in fathers as they hold their children or play with them.
The study, by Emory University in Atlanta, Georgia, raises the possibility that oxytocin could be artificially given to fathers who are failing to bond with their children. It is available in a simple nasal spray.
Earlier this week a separate study suggested that at least 30,000 British fathers suffer from depression following the birth of a child.
One of the causes of post-natal depression, which has never been recognised in men before, is thought to be a failure to bond.
"Our findings add to the evidence that fathers, and not just mothers, undergo hormonal changes likely to facilitate increased empathy and motivation to care for their children," said study leader James Rilling.
"I'm interested in understanding why some fathers are more involved in caregiving than others.
"In order to fully understand variation in caregiving behaviour, we need a clear picture of the neurobiology and neural mechanisms that support the behaviour."
His team's study found dads dosed with oxytocin showed a much stronger emotional response to pictures of their baby.
The researchers scanned the brains of 30 fathers while showing them pictures of their own baby, a photo of a child they did not know and a photo of an adult they did not know.
When viewing an image of their offspring, participants dosed with oxytocin showed significantly increased neural activity in brain systems associated with reward and empathy.
The study is published in the Hormones and Behaviour medical journal.