Our kids are growing up so fast these days. This seems especially obvious in girls, whose play often gives way to talk of boyfriends at an early age, and who nowadays become "fashion victims" even before leaving primary school.

There is also evidence girls are physically maturing at an earlier age than in previous generations, and this can create real issues, since girls who reach puberty earlier are at increased risk of depression, anxiety and breast cancer – not to mention teenage pregnancy.

The main predictor of pubertal timing is genetic, and if a mother reached puberty at an early age, then the chances are her daughter will do the same. Money and status also play a role, with daughters in families farther up the socioeconomic ladder tending to mature later. But two recent studies published in the journal Child Development show that our family relationships as we are growing up can have a significant impact on the timing of our sexual development – with repercussions for the rest of our lives.

It seems the quality of our relationship with our parents is particularly important. In a study following the fortunes of 180 girls from preschool to age 11, Bruce Ellis, of the University of Arizona, and Marilyn Essex, of the University of Wisconsin, found that warm, positive relationships with mothers and fathers, and less marital conflict as reported by fathers, all forecast later pubertal development in daughters.

Jay Belsky, of Birkbeck College in London, and his colleagues carried out another long-term study, this time of 397 girls, where family relationships were evaluated and physical measures were carried out on the girls each year to assess their stage of maturation. This study also found a significant link between parenting styles and the timing of sexual development, though while Ellis and Essex found that positive parenting had the most obvious effect, the results of Belsky emphasised the role of negative parenting: in particular, maternal harsh control was associated with earlier puberty in daughters.

Belsky distinguishes between authoritative and authoritarian parenting, saying: "An authoritative parent is going to explain, is going to reason, is going to be sympathetic and empathic and understanding and encouraging."

On the other hand, the harsh-control, authoritarian parent is more likely to be demanding or angry, perhaps physically punishing, giving the child fewer choices, and it is this type of emotionally negative environment that seems to lead to earlier puberty.

But why should our sexual development be linked to family relationships?

"The ultimate goal of all living things is to reproduce, to distribute their genes across generations," says Belsky.

So what's the best way of doing this? If you grow up in a family with plenty of resources – emotional, financial and nutritional – then it makes sense for the body to grow and get healthy and to defer reproduction so you can be in a position to find the best partner possible, he says. Then you can invest highly in a few children.

On the other hand, Belsky adds: "A stressful family environment provides a forecast suggesting that the future is precarious, that relationship supports are uncertain and that it may be a fool's errand to delay pregnancy and reproduction, because in the future life may be even riskier and resources may be even scarcer."

So you mature fast and start reproducing. But this all begs the question: how can social and emotional experiences influence physical development?

It could be down to body weight. When we are stressed we tend to tuck into comfort food – high in fat and sugar – and our body mass index (BMI) increases. Children growing up in a high-stress family may be likely to consume such food. Given that greater weight is associated with earlier pubertal development in girls, Ellis and Essex considered weight gain through stress as a potential route through which the family environment could affect maturation. (...)

Source: Scotsman, United Kingdom http://news.scotsman.com/scitech/Both-nature-and-nurture-play.3737586.jp