Why married men tend to behave better

The answer, according to a new study led by a Michigan State University behavior geneticist, appears to be both.

In the December issue of the Archives of General Psychiatry, online December 6, S. Alexandra Burt and colleagues found that less antisocial men were more likely to get married. Once they were wed, however, the marriage itself appeared to further inhibit antisocial behavior.

"Our results indicate that the reduced rate of antisocial behavior in married men is more complicated than we previously thought," said Burt, associate professor of psychology. "Marriage is generally good for men, at least in terms of reducing antisocial behavior, but the data also indicate that it's not random who enters into the state of marriage."

The study is the first to investigate the effects of marriage on antisocial behavior using a genetically informative twin sample to rule out the effects of genes on these associations. The researchers examined the data of 289 pairs of male twins. The twins were assessed four times, at ages 17, 20, 24 and 29.

The study found that men with lower levels of antisocial behavior at ages 17 and 20 were more likely to have married by age 29 (researchers refer to the act of entering into marriage as a selection process). This is noteworthy since previous studies found little support that selection process influenced reduced rates of antisocial behavior among married men.

Burt said her finding may differ from past studies because marital rates have declined significantly in recent years, whereas marriage was more of the norm in the 1950s, meaning selection likely wasn't much of a factor.

Once the men were married, rates of antisocial behavior declined even more. When comparing identical twins in which one twin had married while the other had not, Burt said, the married twin generally engaged in lower levels of antisocial behavior than did the unmarried twin.

Burt said it's unlikely that marriage inhibits men's antisocial behavior directly, but rather that marriage is a marker for other factors such as social bonding or less time spent with delinquent peers. Another factor that seems to be important is marriage quality; the effect of marriage on antisocial behavior tends to be stronger in better marriages.

Burt's co-researchers are M. Brent Donnellan and Mikhila Humbad from MSU; Brian Hicks from the University of Michigan; and Matt McGue and William Iacono from the University of Minnesota.