A new study by the University of Michigan has shown the link between testosterone levels and male parenting.
Researchers found that men's testosterone levels lowered when they saw their infants in distress, leading to a more nurturing response. This, combined with a positive relationship with the infant's mother, were found to be factors in differentiating whether a father was nurturing or not.
For fathers who felt aggravated by their children's crying, testosterone levels could go up and lead to a more negative response.
The study took into account 175 men whose partner was pregnant with a second child and measured hormone levels via saliva samples with father-infant interaction.