|
Study Debunks Theory On Teen Sex,
Delinquency New Analyses Challenging Many Old Assumptions
November 11, 2007
By Rick Weiss
Researchers at Ohio State
University garnered little attention in February when they found
that youngsters who lose their virginity earlier than their peers
are more likely to become juvenile delinquents. So obvious and well
established was the contribution of early sex to later delinquency
that the idea was already part of the required curriculum for
federal "abstinence only" programs.
There was just one problem: It is
probably not true. Other things being equal, a more probing study
has found, youngsters who have consensual sex in their early-teen or
even preteen years are, if anything, less likely to engage in
delinquent behavior later on.
That new analysis, a reworking of
the same data the Ohio team used, is one of several recent instances
in which a more precise parsing of data has begun to turn
long-standing societal presumptions on their head. By bringing
evidence to bear on complex social issues, these studies are forcing
individuals and policymakers to rethink such hot-button topics as
the benefits of breast-feeding, the risks of teen child-bearing and,
in the latest example, the harms long presumed to result from teen
sex.
Like many of the newer studies, the
latest one -- led by Paige Harden, a doctoral candidate in
psychology at the University of Virginia in Charlottesville -- used
the powerful techniques of behavioral genetics. The field
specializes in studies on twins, research that can help tell whether
behavioral traits are the result of genes or the social environment,
and that has periodically stirred controversy when it has focused on
the genetic underpinnings of criminality and intelligence.
But the specialty's analytic
methods can also help tell whether one behavior, such as early sex,
is merely correlated with or actually causes a second behavior that
is often found with it, such as delinquency. If two behaviors often
exist in the same people but are found not to be connected by cause
and effect, then a third factor is likely to be causing both.
That kind of finding can help
identify better targets for prevention efforts, experts say.
"Behavioral geneticists have long
sought to establish causal links between genes and complex
behaviors. So it's fascinating to see them use the tools of their
trade to dispute widely held beliefs" about the social roots of some
of those behaviors, said Erik Parens, a senior research scholar who
has tracked the field intensively at the Hastings Center, a
Garrison, N.Y., science and ethics think tank.
The latest example started when
Dana Haynie, a sociologist at Ohio State, and her then-graduate
student, Stacy Armour, published a study in February in the Journal
of Youth and Adolescence. They analyzed data collected from more
than 7,000 children as part of the National Longitudinal Study of
Adolescent Health, a federally funded survey that in 1994 began
gathering information about the health-related behavior of U.S.
schoolchildren who were then in grades seven through 12.
Haynie and Armour divided the
children into three groups based on when they first had sex: when
they were younger, about the same age or older than the age at which
most of their local peers lost their virginity. (It varies by
region, but on average, U.S. children lose their virginity at age
16.) They also compiled information on graffiti-painting,
shoplifting, drug-selling and other "problem behaviors" by those
young people in later years.
Their conclusion: One year after
losing their virginity, children in the early category were 20
percent more likely than those who started having sex at the average
age to engage in delinquent behavior, even when several other
relevant factors such as wealth, race, parental involvement and
physical development were taken into account.
Those findings supported the widely
held notion that loss of virginity at a relatively young age appears
to, as Haynie and Armour wrote, "open the doorway to problem
behaviors."
Harden, at the University of
Virginia, didn't believe it.
Looked at from a similarly high
altitude, she said, people might conclude that red meat is a health
food, since people live longer in countries where more is eaten.
Only when the issue is studied within one country does red meat's
link to chronic diseases appear.
Suspecting such an error in the
Haynie study, Harden and three colleagues, including her adviser,
Eric Turkheimer, an expert in behavioral genetics, studied more than
500 pairs of twins in the same national survey analyzed by the Ohio
team. Because twin pairs share similar or identical genetic
inheritances (depending on whether they are fraternal or identical)
and the same home environment, twin studies are useful for seeing
through false cause-and-effect relationships.
The team looked at identical twin
pairs in which one twin initiated sex younger than the other, then
team members tallied subsequent problem behaviors. If sex really
adds to the chances of delinquency, then early-sex teens should end
up delinquent more often than their later-sex twins.
"It turns out that there was no
positive relationship between age of first sex and delinquency,"
Harden said.
The way to reconcile that with the
previous evidence of a link is to conclude that some other factors
are promoting both early sex and delinquency, she said. In an
e-mail, Haynie agreed. And the Virginia study, to appear in the
March 2008 issue of the Journal of Youth and Adolescence, offers
some clues.
It found that identical twins, who
have the same DNA, were more similar to one another in the ages at
which they lost their virginity than were fraternal twins, whose DNA
patterns are 50 percent the same -- an indication that genes
influence the age at which a person will first have sex. Other twin
studies have found the same pattern for delinquency.
Together, those findings suggest
that some genes -- perhaps, for example, those that increase
impulsivity and risk-taking -- may underlie both behaviors.
"You need to have some appetite for
risk-taking to be a delinquent. And the same if you're 13 and going
to have sex for the first time," Harden said.
Efforts to prevent delinquency can
hardly take aim at people's genes. But the Virginia study also
indicates that social factors, as yet unidentified but perhaps
involving relationships with family and friends, have an even bigger
impact than genes on whether a child will become delinquent. Those
are the things that should be identified and targeted by
delinquency-prevention programs, said Jeanne Brooks-Gunn,
co-director of Columbia University's National Center for Children
and Families.
"I wouldn't be focusing on early
sexuality . . . to alter rates of delinquency," she said.
Perhaps most surprising, the
Virginia study found that adolescents who had sex at younger ages
were less likely to end up delinquent than those who lost their
virginity later. Many factors play into a person's readiness for
sex, but in at least some cases sexual relationships may offer an
alternative to trouble, the researchers say.
Even then, there are emotional and
physical risks. Young adolescents, in particular, are less likely to
use condoms and so are vulnerable to sexually transmitted diseases
and unwanted pregnancies.
But those are risks that other
nations have mitigated with education, Harden and Turkheimer said,
while U.S. educators wanting a piece of the nation's $200 million
"abstinence only" budget must adhere to a curriculum that links sex
to delinquency and explicitly precludes discussion of contraception.
The new study "really calls into
question the usefulness of abstinence education for preventing
behavior problems," Harden said, "and questions the bigger
underlying assumption that all adolescent sex is always bad."
Similar re-analyses have begun to
undermine other conventional notions about health.
A recent study by Scottish
researchers asked whether the higher IQs seen in breast-fed children
are the result of the breast milk they got or some other factor. By
comparing the IQs of sibling pairs in which one was breast-fed and
the other not, it found that breast milk is irrelevant to IQ and
that the mother's IQ explains both the decision to breast-feed and
her children's IQ.
In another example, Arline
Geronimus, a University of Michigan professor of health behavior who
is now a fellow at Stanford University's Center for Advanced Study,
knew that babies born to teenagers are more likely to die in their
first year of life than those born to older women.
"But that is an apples-to-oranges
comparison," she said. In New York City, for example, far more teen
mothers live in Harlem than on the Upper East Side, she said, and
"there are a lot of differences between those groups."
So Geronimus looked more closely
and got a different answer.
"If you compare Harlem teen moms to
Harlem older moms, you find that the kids of the teen moms are
actually less likely to die," she said. The reasons include the fact
that, unlike older women, poor teenagers are generally not juggling
jobs and have older relatives to help.
It can make sense for poor women to
have children when they are quite young, Geronimus concludes, and
any effort to change that ought to treat it as an economic problem,
not a health education problem.
In a different re-analysis,
Geronimus made another counterintuitive finding. While it is true
that, in general, teen mothers are less likely to breast-feed their
babies than older moms, it is not true among poor women. Poor
teenagers are actually more likely to breast-feed than poor older
moms, in large part because the older women have jobs that don't
grant them the time to breast-feed or pump milk.
Because of that misconception,
programs promoting breast-feeding have targeted teens instead of
older women, Geronimus said. And they have taken aim, in part, at a
concern that teenagers were believed to have: the cosmetic effects
of breast-feeding on their breasts.
"So you've targeted the wrong
population," Geronimus said, "and come up with the wrong kind of
intervention."
|
