New step reported in untangling nature vs nurture           

RANDOLPH E. SCHMID, AP Science Writer

WASHINGTON – Untangling the mystery of inherited

versus acquired traits may be a step closer. Arguments

have been long and contentious over how much people

inherit and how much they are influenced by their

environments.

Researchers led by Frances Rice and Anita Thapar of

Britain's Cardiff University focused on reports that

smoking by the mother during pregnancy increased the

chance of low birth weight and anti-social behavior in

children.

The researchers studied 533 children who were

genetically related to the mother that carried them and

195 who resulted from egg donations and thus were not

genetically related to the mother. The children were aged

from 4 to 10 and had been conceived at clinics in the

United Kingdom and United States.

"What we have been able to confirm is that cigarette

smoke in pregnancy does lower birth weight regardless of

whether the mother and child are genetically related or

not," Thapar said.

However, that was not the case with anti-social behavior

in children, such as temper tantrums, fighting, bullying and

disobedience.

They found that smoking during pregnancy was

associated with higher levels of anti-social behavior in

children who were genetically related to their mothers, but

not in children of unrelated mothers.

"It is now clear that offspring anti-social behavior is more

dependent on inherited factors passed from mother to

child, as our group of children with mothers who smoked

during pregnancy with no direct genetic link showed no

increased signs of anti-social behavior," Thapar said.

"This suggests that other influencing factors such as the

mother's personality traits and other inherited

characteristics are at play during the development of a

baby."

Such findings can help guide efforts to improve children's

health, she said. For example, having the mother quit

smoking is clearly important in improving a child's birth

weight.

But it may be better to spend money on parenting skills 

after birth than on arguing that quitting smoking could

improve children's behavior, she added.

The results were reported in Tuesday's edition of the

Proceedings of the National Academy of Sciences.

Thapar said the researchers are planning further studies

on attention deficit-hyperactivity disorder, emotional

symptoms, health outcomes and stress.

"The average reader needs to be careful and clear about

what sorts of prenatal interventions are going to be helpful

for what sorts of child health outcomes, so that public

health money is spent in an effective fashion," she said in

an interview via e-mail.

On the Net:

PNAS: http://www.pnas.org

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