Says Hasse Walum, the leader of the study :

“The hormone oxytocin seems to influence female pair-bonding more, and we are planning to investigate if variation in the gene coding for the receptor for this hormone is associated with women’s pair-bonding behaviour.”

Oxytocin hardwires men to cuddle their babies too.

After measuring 80 couples’ levels of oxytocin — the “cuddle hormone” that supports touching, hugging, holding and trusting others — an Israeli doctor found that fathers as well as mothers post increases after childbirth. Oxytocin has a powerful effect on the brain, making people feel less anxious and more calm, trusting and connected.

Oxytocin is usually studied in connection with women and bonding, labor, delivery and breastfeeding. But fathers of newborns actually have oxytocin levels comparable to mothers’, based on Dr. Feldman’s findings

Altruism linked to oxytocin genes

Researchers at an Israeli university have identified a link between altruistic behaviour and a specific variation in a persons DNA that acts as a brain receptor for oxytocin.