Twin Research Links Genetics and Adult Spirituality

March 21, 2005 — -- The Georgia woman who reportedly convinced an alleged gunman to end his killing spree said she and Brian Nichols talked about their families, the Bible and their faith.

"I believe God brought him to my door," Ashley Smith told reporters after calling 911 and alerting police that Nichols, the suspect in the slayings of four people, including an Atlanta judge, was in her apartment.

Smith's faith may have led her to believe that Nichols targeted her for a reason, but scientists are asking what makes people like Smith maintain their faith in the first place.

If new research is to be believed, when it comes to fostering religious adults, genetics play a significant role.

Recent studies with twins show that while environmental factors play a big part in determining a person's degree of faith early in life, later on genetics take over and become a dominant factor as people make the transition into adulthood and either strengthen or reduce the role of religion in their lives.

"Our findings show that the differences in religiousness among individuals are due in part to genetic differences among individuals," said Laura Koenig, a graduate student at the University of Minnesota in Minneapolis and lead author of the twin study in the current issue of the Journal of Personality.

This could mean that people like Smith are, to some extent, hardwired in their faith.

Comparing Faith Among Twins

To get at possible causes behind a person's degree of religiousness, Koenig examined surveys completed by 169 identical and 104 fraternal twins. All the twins were men born in Minnesota with an average age of 33 at the time of the survey. The idea was that similarities in faith between identical twins would have a stronger genetic link that those found among fraternal twins.

In the surveys, the men graded how often they took part in religious activities and the importance of religious faith in their lives. They also rated their mother and father's level of faith, as well as their own while they were growing up. Finally, they were asked to grade the current and past religious faith of their twin.

Koenig then compared how similar faith levels were between the identical twins, who share 100 percent of their genes, and the fraternal twins, who share half of their genes, to get a sense of how much genetics may be influencing their faith. The results, she said, "showed that the environment had a large effect on religiousness in childhood," while for adults, "the reverse was true -- genetic effects were stronger."

The findings are a fresh take on previous research that has hinted at a genetic root for spirituality. Among the first was a 1979 twin study at the University of Minnesota, led by one of Koenig's co-authors and advisers, Thomas Bouchard, a psychologist at the school.

In this now-famous study, the researchers tracked down 53 pairs of identical twins and 31 pairs of fraternal twins who had been separated at birth and raised in different settings. The researchers then looked for traits in common to try and separate the influences of genetics and environment.

Among the many areas where identical twins showed strong overlap was spirituality -- they were twice as likely as fraternal twins to share as much or as little faith as their long lost sibling. There was a weaker genetic link, however, when the researchers assessed how much each twin practiced his or her religion, in terms of attending services or observing rituals.

"I think it is important to distinguish religion in terms of things like going to church and following a creed. That tends to be very much influenced by the patterns of your parents," said Robert Cloninger, a psychiatrist at Washington University in St. Louis and co-designer of a test used in psychiatry to assess character and spirituality. "Spirituality, meanwhile, has to do with a way of feeling and thinking, which tends to lead to an acceptance of the role of a higher intelligence. Studies show there are specific receptors in the brain that influence a person's ability to get into that mode of thought."

If hardwiring for spirituality exists, is it there for a reason? Some argue it's there for a very important purpose -- survival.

Survival of the Most Spiritual?

"There is logic behind why humans may have evolved with a religious predisposition in their genes -- it has health, pro-social behaviors and psychological advantages," argues Harold Koenig (no relation to Laura Koenig), a psychologist and co-director of the Center for Spirituality, Theology and Health at Duke University. "Hope, optimism helps people to survive despite difficult life circumstances."

Koenig's center has conducted more than 25 studies over the past 20 years looking at the relationship between religion and physical and mental health. He says the work has shown a clear link between good health and spirituality, except in less common cases where unwell people feel they have been 'punished' by God.

Assuming religion does carry a health benefit, as Harold Koenig's studies suggest, then, he says, it makes sense that evolution would favor a genetic disposition for spirituality. Dean Hamer, a geneticist at the U.S. National Cancer Institute has made similar arguments in his book, "The God Gene: How Faith Is Hardwired into Our Genes."

But these researchers also stress that genetics certainly don't act alone when it comes to influencing a person's level of faith. In fact, as people age and approach the possibility of death, or when individuals, such as alleged hostage victim Smith and shooting suspect Nichols are facing an extreme fate, Harold Koenig argues that outside circumstances inevitably start to play a stronger role.

"When you're confronted with issues that take away control of your own life, environmental factors will be stronger," he said. "Genes are still at play, but for the moment they take the back seat."