Monday, 2 April 2012

Why did I do that?

A Glimpse into Plasticity Genes

Ever wondered why some people are more generous than others? You might think it has to do with how a person has been raised or because simply because it’s who they are. You’d be right both times. Recent studies have shown that genetics plays a vital role in deciphering the origins behind a person’s behavioural traits, but is not the reason behind it all.

It all began with an experiment in which a 3-year old spends an hour playing games with a woman. They then go to eat a packet of corn puffs each. The child opens theirs to find a normal amount but the woman only has a few in her bag and she becomes upset. The question is then put forward, will the child instinctively share their corn puffs with the woman? The results of the experiment show that while most of the children tested did not willingly share, a few did and further testing suggested the reason why.
The children who were more likely to share possessed a particular variant of the DRD4 gene, one that affects the amount of dopamine released in the brain. Dopamine is a neurotransmitter which is responsible for feelings of satisfaction and reward, thereby allowing the child to happily give their corn puffs away. While the results seem straightforward, the DRD4 gene variant known as “7R” had been previously dubbed names such as “the brat gene” and “the ADHD gene.” (Dobbs, 2012) If this gene had been thought to be nothing but bad news for children, then why was it having such a good effect?

A new theory emerged from this and similar tests, the “plasticity theorem.” The basis of this idea is that the possession of a certain gene does not simply mean a child is more inclined towards a certain string of behaviour, but instead that they are more easily affected by their environment. This is theory has also resulted in the development of two new terms, “orchid children” and “dandelion children.” The reasons being that an orchid children require a stable, nurturing environment in order for them to flourish while a dandelion can survive in harsh surroundings. 
What this means is that a child carrying this previously ill-fated “7R” gene variant is now thought to have far greater potential and is more likely to thrive in the proper environment. In contrast, a negative environment is also far more likely to result in negative effects on the child’s behaviour. This effect has been found in many other gene variants such as a gene called MAOA which affects a person’s levels of serotonin and the short SERT, previously named “depression gene.” 

 While dandelion children are not so easily affected by their environment, it is said that the more sensitive orchid children are more responsive “to many of life’s pleasures and subtleties.” (Aron, 1999) While not everything is yet known or understood about genetic behaviour, the interpretation of this new discovery can definitely be regarded as a step in the right direction. 

by Andrew Yong Gee (42885001)

Aron E, 1999, The Highly Sensitive Person: How to Thrive When the World Overwhelms You, Crown Publishing Group, New York

Belsky J, Vulnerability Genes or Plasticity Genes?, Molecular Psychiatry, 19/05/2009, Vol. 14, p. 746-753

Dobbs D, The Orchid Children,  New Scientist, 1/28/2012, Vol. 213 Issue 2849, p42-45

Ellis B, Boyce W T, Differential susceptibility to the environment: Toward an understanding of sensitivity to developmental experiences and context, Development and Psychopathology, 24/01/2011, Vol. 23, Issue 1, p. 1-5

Knafo, Ebstein & Israel, Heritability of children's prosocial behavior and differential susceptibility to parenting by variation in the dopamine receptor D4 gene, Development and Psychopathology, 24/01/2011, Vol. 23, p. 53-67

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