"A lot of it comes down to gender role stereotypes and role modelling," he said.
"One of the things that became obvious straight away is in the girls' schools where we conducted the research, the principal, deputy principal, registrar, all the of the heads of department are women. So the girls are seeing strong leadership role models."
The study also found significant differences between the types of chores undertaken by boys and girls, with boys more likely to engage in outdoor chores compared to girls and also more likely to get extra pocket money for doing so.
It recommended, along with ensuring equity in the activities and chores girls participate in, parents and caregivers should also ensure they talk to their children about the stereotypes they see in the media to actively try to dispel these.
Numerous studies show girls' confidence levels fall below boys' as early as the age of nine, and that gap does not close until they are about 80.
But this study found no significant differences in self-confidence between girls and boys at single-sex schools.
Doctor Fitzsimmons said similar studies at co-ed schools have found gender attitudes that reflect what is happening in the workplace.
He said subliminal attitudes around what girls can and cannot do are more of an issue in co-ed schools in areas such as subject choice and sport.
"We have identified that team sports was the biggest contributor to self-efficacy development. But it is well known that girls opt out of sport in adolescence way more than boys do. And that is certainly not something we found in the single-sex schools."
But Dr Fitzsimmons said the survey revealed even in single-sex schools boys are spending more time relative to girls on outdoor activities and team sports in particular.
Parramatta Women's Grade Cricket Club in Western Sydney plays association cricket - a game traditionally played by boys.
But President Scott Reibelt said two years ago they decided to take on 12 girls to play in the team with positive results.
"We don't segregate between boys and girls. And they actually give it to the boys just as much as the boys give it to them."
"There is that mutual respect you do get in cricket, where all players do respect each other and they are satisfied with their results at the end of the day.
Kesley Myers, an all-rounder in the team, said it was initially daunting playing against the boys.
But she said her confidence levels have increased since playing side by side with the boys.
"Definitely it has helped knowing that you have been playing against stronger boys I guess. And knowing that you are the same age as them and you are capable of doing that it is really empowering."
Dr Fitzsimmons' next step is to replicate the study in co-ed, private and public schools.