Girls with older brothers go through puberty later, according to research by the University of Western Australia.
The study also found that having a brother - older or younger - helps keep girls on the straight and narrow.
Other findings in the study - which questioned three hundred men and women about their family and lives - indicated girls with older brothers began their periods almost a year later than those with younger siblings of either sex.
The gender make up of a family also had an effect on the age which a girl became sexually active - whilst having older brothers or sisters had little impact, girls with younger siblings tended to delay their first sexual experience. Girls with younger brothers and sisters were also found to have had sex over a year later than only children.
Fritha Milne from the university's research team said: 'Elder daughters may provide more help to their parents in raising younger brothers than do elder brothers. Associated with this prolonged help is a delay in sexual activity.'
What do you think?
Has having an older brother kept you on the straight and narrow?
Is your daughter less mature than her sibling-less peers?