A national study of 13-year-olds in Ireland has shown that one in ten would not approach anybody for information on sexuality.

Almost 7,500 teenagers were interviewed for the study and were asked who they would most likely turn to for information on relationships and sexuality.

Over four in ten said they would ask their mother, but only 6% (all boys) opted for their father.

Almost a quarter of those interviewed favoured going to friends, while 9% said they depended on teachers; 6% depended on the internet and print media, but 10% said they would go nowhere for such advice.

The study – ‘Growing Up In Ireland’ – was sponsored by the Department of Children and Youth Affairs.

Senior civil servant Jim Breslin called the sex education findings “worrying”.

He said it was very important that his Department continued to develop and support the consistent teaching of Relationship and Sexuality Education.

The study also found that 60% of 13-year-olds exercised six or more days in a fortnight, but almost a quarter of those surveyed were overweight or obese.

Almost 40% of girls in the age group were trying to lose weight.

The research found that the number of their families reporting financial difficulties had doubled since the group was last interviewed four years ago.

They said the most frequently recorded effects were reduction in wages and social welfare payments, and families not being able to afford luxuries.

All of those interviewed for this study had been previously interviewed at aged nine.

The survey showed they were mostly positive about school and their teachers. However, 13-year-olds in first year were more positive than 13-year-olds in second year.

The principal investigator of the study said obesity has a huge impact on a child's life and would have an effect in their later lives.

Speaking on RTÉ’s Morning Ireland, Professor James Williams, said that being overweight as a young person increases the risk of developing illnesses such as asthma and diabetes.

He said the study showed differences in terms of gender and in terms of the social background and that boys were more inclined to exercise than girls and it was more common for children from socially advantaged backgrounds to exercise.

Prof Williams said the study showed that children who are overweight and obese are trying to do something about it.

It also showed that children are getting on well with their parents and they said they have more fun with their fathers.

He said the study did show some disengagement as students progress through the second level school system.