Nature Joins Nurture to Boost Divorce Risk
Bower, Bruce, Science News
Increasing social acceptance of marital breakups over the past century has helped spur an increase in the U.S. divorce rate from near zero to roughly one in two couples who exchange vows. Nevertheless, a new study indicates that people who split from their spouses often carry a genetic risk for such behavior -- perhaps an inherited tendency toward impulsiveness or some other personality characteristic -- that operates in collaboration with family experiences and cultural attitudes toward divorce.
"Genetic factors, such as temperament, help to determine the kind of experiences a developing child has and seeks out, and [they] eventually influence many real-world behaviors, including divorce," asserts David T. Lykken of the University of Minnesota in Minneapolis.
Lykken and University of Minnesota colleague Matt McGue, both psychologists, present their findings in the November PSYCHOLOGICAL SCIENCE.
The researchers obtained self-reported marital histories from 1,516 same-sex twin pairs born in Minnesota between 1936 and 1955. Slightly more fraternal twins (who share, on average, half the same genes) than identical twins (who share essentially all the same genes) responded to the survey. Of the twin pairs, 953 were women and 563 men.
Participants not only reported their own marriages and divorces, but offered what they knew about those of their parents and their spouses' parents.
Divorce occurred substantially more often among both identical twins than among both fraternal twins, Lykken and McGue maintain. This finding held for men and women, twins younger and older than 40 years, and twins whose parents both had been and had not been divorced.
However, the risk of divorce for a participant rose significantly if his or her parents or spouse's parents had divorced. If both sets of parents had divorced, the risk of divorce doubled over that calculated when one set had split up.
Previous studies have considered the family background of only one divorced spouse, thus underestimating the extent to which divorce serves as an ironic tie that binds generations, the researchers note. …