Genetic roots of 'orchid' children

http://www.sciencenews.org/view/generic/id/72280/title/Genetic_roots_of_orchid_children

By Bruce Bower
Web edition : Wednesday, April 6th, 2011

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 Danielle 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, Davis.

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 Michael Pruess, a Davis colleague of Belsky’s.

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