Baby clue to eternal debate

Test tube babies are offering scientists a novel laboratory for resolving one of the most vexing debates in science: nature versus nurture.

British researchers have studied children conceived through in vitro fertilisation to examine whether children whose mothers smoked during pregnancy were likely to develop behavioural problems because of the toxic effects of smoking, or because their mothers passed on a genetic predisposition to antisocial behaviour.

Anita Thapar, a professor of child and adolescent psychiatry at Cardiff University in Wales, and her colleagues examined whether children whose mothers smoked were more likely to have been born underweight and whether they developed behavioural problems, such as temper tantrums or frequent fighting.

The researchers found that the children whose mothers smoked were likely to be born underweight, regardless of whether they were genetically related to them.

But antisocial behaviour was more common only in children who were genetically related to mothers who smoked, indicating that a genetic influence was at work.

Thapar said: “Other factors, such as a mother's personality traits and other inherited characteristics, are at play during the development of the baby. This says if you find a particular risk factor that looks like prenatal nurture, be careful — it may really be nature.''

But smoking clearly increases the risk of being born underweight, which can increase the risk of a host of medical problems.