Researchers had long speculated that early-developing girls were nudged into delinquency because they had more older friends, and more male friends.
But, instead, new research suggests that the key factors appear to be the fact that these girls are dating and that they have more friends - regardless of age - who are already involved in delinquency.
"Girls who develop early aren't any more likely to have male school friends, or older school friends than their less developed counterparts," said Dana Haynie, author of the study and assistant professor of sociology at Ohio State University.
"But going through puberty early does expose these girls to other social factors that put them at risk for delinquency."
The study appears in the September 2003 issue of the journal Social Forces.
Haynie used data from the ADD Health project, which surveyed a nationally representative sample of adolescents in grades 7 through 12 in 1995 and 1996. Data from a total of 5,477 young girls were included in this study. The girls were asked a variety of questions about their physical development, their participation in delinquency, and their relationships with friends and parents. Their parents and friends were also interviewed.
Overall, as expected, girls who were more physically developed than their peers in the same grade were more likely to be involved in all types of delinquency, from minor to violent.
For example, girls who were highly developed compared to their peers had a 27 percent increase in minor delinquency - such as shoplifting and vandalism -- compared to those with average development.
Moreover, girls who were less developed than average showed lower levels of delinquency than those experiencing average pubertal development, the study showed.
While the number of male friends and older friends were not associated with delinquency, dating did have an effect. The study found that early-developing adolescents involved in romantic relationships had a 35 percent increase in the least serious forms of delinquency such as smoking cigarettes and marijuana, drinking alcohol, lying to parents and school truancy. Almost two-thirds of more-developed girls were involved in a romantic relationship, compared to 41 percent of less-developed girls.
In addition, adolescents whose friends all participated in minor delinquency such as drinking, smoking and skipping school had an 118 percent increase in delinquency compared to girls whose friends were not involved in such behaviors. And more developed girls do have slightly more delinquent friends, on average than other girls: 77 percent of their friends are involved in delinquency, compared to 72 percent of average developers and 69 percent of less developed girls.
Haynie said relationships with friends seem to have the greatest effect on delinquency among early-developing girls.
"What I found is that parent-child relationships were playing a role, but it seemed to be a smaller role than did the relationships with friends," she said. Parental-child relations were most important in explaining serious delinquency.
"Perhaps it takes more antagonism between a parent and child to push girls into serious delinquency, while their involvement in minor delinquency reflects more of a pull from their friends," she said. Haynie said the results show how biological and sociological factors in adolescents interact to put some girls at higher risk for involvement in delinquency.
"Biology does not provide a direct route to delinquency. In this case, there is a biological characteristic - early puberty - that seems to place girls in social contexts where delinquency is more likely," Haynie said. "Other studies have shown the connection between early puberty and delinquency, and this study is helping to account for that association."
But why would early development affect these social contexts?
While this study can't directly answer these questions, Haynie said it may be that the visible physical changes in appearance that result from puberty may signal to the girls themselves and others that they are ready for adult-like roles.
"When adolescents enter puberty, they are looking for more adult roles and it may be that dating and finding friends who are involved in delinquency are ways they can satisfy their desire to me more like adults," she said.
Girls who are undergoing early physical maturity may also feel they are ready for more adult roles and rebel against parental restrictions that they feel are too strict, she said.
The problem, Haynie said, is that early-developing girls are experiencing the pressures of puberty at such a young age that they may not yet be emotionally and psychologically prepared.
"Unfortunately, dating and involvement in minor delinquency have been shown to be especially detrimental to adolescents engaging in the behaviors at very young ages," she said.