Good mother-daughter relationships may also delay the onset of sexual maturity, according to a report in the Journal of Personality and Social Psychology.

The research team from the Vanderbilt University in Nashville, Tennessee, found that the "quality of fathers' investment" was the most important factor in their study of development.

Bruce Ellis, who led the research, followed the progress of 173 girls for eight years, starting before they entered education.

He found that fathers who were observed to be more affectionate with their daughters, and who spent more time caring for them before they reached school, tended to have daughters who entered puberty later than girls who had poorer relationships.

Reason a mystery

The team is still baffled by the exact cause of this delay, although Mr Ellis speculates that stress may be to blame.

He said: "It may be the particular kind of stress associated with either low levels of positive family relationships, a lack of paternal investment, or both, that provokes earlier puberty."

A good mother-daughter relationship also delays puberty

The researchers also believe that exposure to unrelated adult males might also bring on earlier puberty.

This is because animal research finds that females exposed to chemicals from unrelated males moved to sexual maturity more swiftly.

Mr Ellis said: "It may be that girls from paternally deprived homes are more likely to become exposed to the pheromones of stepfathers and other unrelated adult males, which in turn accelerates pubertal development."

Possible flaw in study

However, one significant factor which could have a major impact on early puberty was not taken into account, said Mr Ellis.

Genetic differences which makes girls mature earlier can be passed from mother to daughter.

And these early-maturing women have an increased risk of becoming sexually active, marrying, and having children earlier, with the subsequent risk of divorce and lack of paternal involvement.