Scientists are claiming that fatherhood can HALVE a man's testosterone levels - and having children stops them from straying!
The study reveals that men with kids have have lower testosterone levels than males with no offspring, and the effect of becoming a dad makes them more interested in settling down and protecting their young than going off and sowing their wild oats.
Scientists in America studied more than 600 men in their 20s over five years. During the process, approximately a third of the participants had a child with their wife or girlfriend, and they were found to have started the experiment with the highest testosterone levels, but, once they'd had their baby, the hormone's production dropped off.
Medics also noted that those who had the biggest depletion in the hormone were the dads who were most hands-on with their youngsters.
The lead researcher of the study, Christopher Kuzawa, the associate professor of anthropology at Northwestern University, told reporters: 'Testosterone boosts behaviours and other traits that help a male compete for a mate.
'Raising human offspring is such an effort that it is cooperative by necessity, and our study shows that human fathers are biologically wired to help with the job.'
Previous research had also found that married men and dads have lower testosterone levels than single men, but this study is the first to actually link settling down and having kids with a fall in the hormone's production.
What do you think?
Did your partner change once you had a family?