Genetic roots of 'orchid' children

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Genetic roots of 'orchid' children

Some kids may inherit sensitivity to family contexts, for better or worse

By Bruce Bower

A Swedish expression that translates as “orchid child” refers to a youngster who

blossoms spectacularly if carefully nurtured but withers badly if neglected.

Scientists have now identified gene variants that may help to cultivate orchid

children by heightening their sensitivity to both good and bad parenting.

In a group of kids tracked from ages 5 to 17, those who inherited certain forms

of a gene involved in learning and memory and had inattentive parents displayed

higher rates of delinquency and aggression than their peers, says a team led by

psychologist le Dick of Virginia Commonwealth University in Richmond.

Children who carried the same gene variants but grew up with involved parents

misbehaved less often than other kids, the researchers report in a paper to

appear in Psychological Science.

Dick’s team focused on CHRM2, a gene that modulates brain transmission of

acetylcholine, a chemical messenger that boosts brain-cell activity. Other

researchers have linked alterations of CHRM2 to a propensity for developing

alcoholism, without looking for contributions of disrupted family relationships

or other environmental factors to that association.

“Our findings suggest that CHRM2 is a plasticity gene involved in creating

biological sensitivity to a person’s environmental context,” Dick says.

A small but growing number of studies suggest that several genes initially

thought to make people prone to developing depression and other disorders do so

only in stressful environments, while carriers of the same genes reap benefits

in supportive settings (SN Online: 1/29/09), remarks psychologist Jay Belsky of

the University of California, .

In a study published online last year in the Journal of Child Psychology and

Psychiatry, Belsky and a colleague found that teenage boys who possess as many

as five previously identified “risk alleles” for various behavioral problems

develop more of those difficulties than their peers if exposed to poor

parenting. Boys who inherit the same genes adjust particularly well in

supportive families, Belsky says.

In 2009, Dick’s team reported similar context-sensitive effects among boys and

girls carrying variants of a gene involved in transmission of a brain chemical

called gamma-amino butyric acid.

A species that adapts to diverse, rapidly changing habitats — such as Homo

sapiens — evolves genes that make some individuals extremely responsive to

environmental conditions, for better or worse, Belsky proposes.

Studies of infant temperament and development indicate that roughly 20 percent

of children qualify as highly sensitive to family environments, estimates

psychologist Pruess, a colleague of Belsky’s.

Dick and her colleagues examined data from 452 boys and girls living in three

U.S. cities who were interviewed annually starting in kindergarten. DNA obtained

from saliva samples was analyzed for nine common alterations of CHRM2.

Kids who inherited any of three variants on both copies of CHRM2 showed

behavioral sensitivity to parental monitoring, a measure of how much parents

know about their children’s friends and activities.

Each child and his or her mother rated that youngster’s delinquent and

aggressive behaviors. Based on those reports, three-quarters of volunteers

experienced modest parental monitoring and 22 percent of parents knew a lot

about their children’s daily whereabouts. Remaining parents knew little about

their children’s lives.

About 14 percent of participants inherited at least one CHRM2 variant associated

with environmental sensitivity. Any brain or other biological effects of these

gene variants remain as elusive as an orchid in a vacant lot