[extropy-chat] Genes contribute to religious inclination

[Joseph Bloch]

http://www.newscientist.com/article.ns?id=dn7147

Genes may help determine how religious a person is, suggests a new study 
of US twins. And the effects of a religious upbringing may fade with time.

Until about 25 years ago, scientists assumed that religious behaviour 
was simply the product of a person's socialisation - or "nurture". But 
more recent studies, including those on adult twins who were raised 
apart, suggest genes contribute about 40% of the variability in a 
person's religiousness.

But it is not clear how that contribution changes with age. A few 
studies on children and teenagers - with biological or adoptive parents 
- show the children tend to mirror the religious beliefs and behaviours 
of the parents with whom they live. That suggests genes play a small 
role in religiousness at that age.

Now, researchers led by Laura Koenig, a psychology graduate student at 
the University of Minnesota in Minneapolis, US, have tried to tease 
apart how the effects of nature and nurture vary with time. Their study 
suggests that as adolescents grow into adults, genetic factors become 
more important in determining how religious a person is, while 
environmental factors wane.
Religious discussions

The team gave questionnaires to 169 pairs of identical twins - 100% 
genetically identical - and 104 pairs of fraternal twins - 50% 
genetically identical - born in Minnesota.

The twins, all male and in their early 30s, were asked how often they 
currently went to religious services, prayed, and discussed religious 
teachings. This was compared with when they were growing up and living 
with their families. Then, each participant answered the same questions 
regarding their mother, father, and their twin.

The twins believed that when they were younger, all of their family 
members - including themselves - shared similar religious behaviour. But 
in adulthood, however, only the identical twins reported maintaining 
that similarity. In contrast, fraternal twins were about a third less 
similar than they were as children.

"That would suggest genetic factors are becoming more important and 
growing up together less important," says team member Matt McGue, a 
psychologist at the University of Minnesota.
Empty nests

Michael McCullough, a psychologist at the University of Miami in Coral 
Gables, Florida, US, agrees. "To a great extent, you can't be who you 
are when you're living under your parents' roof. But once you leave the 
nest, you can begin to let your own preferences and dispositions shape 
your behaviour," he told New Scientist.

"Maybe, ultimately, we all decide what we're most comfortable with, and 
it may have more to do with our own makeup than how we were treated when 
we were adolescents," says McGue.

About a dozen studies have shown that religious people tend to share 
other personality traits, although it is not clear whether these arise 
from genetic or environmental factors. These include the ability to get 
along well with others and being conscientious, working hard, being 
punctual, and controlling one's impulses.

But McGue says the new work suggests that being raised in a religious 
household may affect a person's long-term psychological state less than 
previously thought. But he says the influence from this early 
socialisation may re-emerge later on, when the twins have families of 
their own. He also points out that the finding may not be universal 
because the research focused on a single population of US men.

Journal reference: Journal of Personality (vol 73, p 471)