If you're fed up with a feckless man in your life, don't despair ... there may be an age-old solution.
Becoming a father for the first time really does make men grow up enough to turn their backs on alcohol, cigarettes and even crime, according to researchers.
And the 'transformative effect' of fatherhood is particularly apparent in older men, they claim.
The study reveals that fatherhood made men curb their reckless behaviour, with males in their mid-20s and early 30s more likely to mature when they become a dad than those who are younger.
The U.S.-based scientists say that older men are especially likely to change their ways because they have matured to the point where they are willing to embrace fatherhood and leave bad habits behind.
Researchers from Oregon State University studied 200 males aged 12-31 who were classed as 'at risk' because of their destructive behaviour.
They monitored volunteers annually for 19 years, looking at how their intake of alcohol and cigarettes had changed, as well as the number of crimes they committed.
While previous studies showed that marriage can change a man's negative behavior, they had not isolated the additional effects of fatherhood.
The results, published in the Journal of Marriage and Family, found that men who were well into their 20s and early 30s when they first had children showed greater decreases in crime and alcohol use than their younger counterparts.
Levels of tobacco use dropped among both older and younger men following the birth of their first child, probably because of warnings given over the dangers to infants' health posed by second-hand smoke.
Professor David Kerr, of Oregon State University and author of the study, said: 'Fatherhood can be a transformative experience, even for men engaging in high risk behaviour. This presents a unique window of opportunity for intervention, because new fathers might be especially willing to make behavioural changes.'