Study: Children With Half-Siblings More Likely To Use Drugs, Have Sex
CAPE CANAVERAL, Florida -- Adolescents who have half-siblings with a different father are more
likely to have used drugs and had sex by age 15 than those who have only
full siblings. That's according to new research from Karen Benjamin
Guzzo, an assistant professor of sociology at Bowling Green State
University, and Cassandra Dorius, an assistant professor of human
development and family studies at Iowa State University.
Using data from the National Longitudinal Study of Youth, they
examined a phenomenon known as "multi-partnered fertility" or MPF. This
happens when parents who are not romantically involved with each other
form new relationships and have another child with a new partner.
"It's not new behavior, but it's happening more often as more people are having children outside of marriage," said Guzzo.
According to Guzzo, this is one of the first studies to examine the
effect of parental MPF on children over the long-term, and the only
study that takes into account background factors (such as the mother's
level of education and household poverty) and the number of changes in
family structure the adolescent experienced.
The researchers looked at the connections between this re-partnering
and additional childbearing on adolescent drug use and early sex. They
focused on mothers and first-born children who lived with their mother
most of their lives.
"For children, MPF means having a half-sibling, but it also means,
for first-born children, that they usually experienced their biological
parents splitting up — if they were together at all, lived in a single
mother household for some time, experienced their mother finding a new
partner at least once and perhaps lived with a stepfather, and finally
experienced their mother having a baby with a new partner," Guzzo
explained.
Researchers looked at the mother's educational background, her own
family structure growing up, and whether the child experienced bouts of
poverty. They also examined family factors — whether the father lived
with them at birth, how many family transitions the adolescents
experienced, and whether the mother ever married or cohabited, with the
child's father or another partner.
"We find that first-born adolescents with half-siblings with the
same mother but a different father do have less favorable outcomes
compared to their peers with only full siblings, even after accounting
for the mother's background characteristics, socioeconomic factors the
child experienced growing up, and family instability and structure,"
Guzzo said.
"Adolescents with a half-sibling with a different father are about
65 percent more likely to have used marijuana, uppers, inhalants,
cocaine, crack, hallucinogens, sedatives, or other drugs by the time of
their 15th birthday than those who have only full siblings. They are
also about 2.5 times more likely to have had sex by their 15th birthday
than their peers with only full siblings."
The findings hit home in Brevard County, where Cape Canaveral was
once was named the divorce capitol in the United States following the
2000 Census. Over a decade later, the divorce rate still remains high
in Brevard.
According to the most recent U.S.
Census data, the divorce rate for females over the age of 15 in Brevard
is 14.6%, over a half percentage point higher than the State of Florida
average of 14%. Thirty-one percent of babies born in Brevard are to
mothers who are unmarried, divorced, or widowed.
Guzzo said it's not clear yet what drives these outcomes, but that
in the future she and Dorius plan to explore differences in maternal
behaviors, father and stepfather involvement, and adolescent perceptions
of their relationship with their mother to see if these factors explain
the association between having half-siblings with a different father
and risky adolescent behavior.
"We are also planning to look at whether this association holds for
children other than the first-born, who tend to experience the most
instability," Guzzo said.