Absent fathers can always expect to get a lot of flak. They’ve already been blamed for their kids’ early sexual maturation, but now research suggests that genes, not necessarily paternal absence, may be the main factor.

Several studies have shown that in households where the biological father is missing, children reach sexual maturity, have their first sexual experience, and are more likely to become teenage parents at a younger age.

Whether that’s down to the stress of not having a father around or the fact that a single mother cannot be as vigilant as two parents has been hotly debated.

Jane Mendle at the University of Oregon in Eugene and her colleagues suspected that genes might play a bigger role than was being acknowledged. The age of sexual maturity and first sexual experience is highly heritable, so she and her colleagues decided to see if the relatives of kids with absent fathers showed the same tendencies.


In the family

They examined data collected for the US National Longitudinal Survey of Youth. Mendle’s team compared 1382 offspring born to women who were genetically related: twins, sisters or cousins. The mothers were interviewed every year between 1979 and 1994, and every two years thereafter.

Their children were interviewed, too, once they reached 14. Among other questions, the children were asked about age at first intercourse.

The researchers found that the more closely genetically related the children were, the more alike they were in age of first intercourse, regardless of absent fathers. Genetics, they argue, has far more influence on this measure than a father’s absence.

Mendle says it is possible that the genes which might make a man more likely to abscond also contribute to early sexual maturation – but not everyone is persuaded by her conclusions.

Bruce Ellis at the University of Arizona in Tucson says the research design controls neither for environment – since the children of sisters grew up in separate households – nor for genes, since the children of sisters share only 12.5 per cent of their genes. And Jay Belsky, a psychologist at Birkbeck, University of London, says the study doesn’t take into account how genes and environment work in combination.

Mendle agrees that genetic explanations and environmental ones often work together, and adds that parents who transmit certain genetic traits can also transmit them socially.

Journal reference: Child Development, vol 80, p 1463