Quick to laugh? It’s in your genes

Why do some people immediately burst into laughter after a funny moment, while others barely smile? New research on emotional reactivity suggests one of the answers may lie in a person’s DNA.

Researchers demonstrated that people with a certain genetic variant — those with short alleles of the gene 5-HTTLPR — smiled or laughed more while watching cartoons or subtly amusing film clips than people with long alleles.

Negative and positive

Previous research has linked the gene to negative emotions; the study provides strongest evidence to date that the same gene is also linked to positive expressions. The research was published online on June 1 in the American Psychological Association journal Emotion.

In the study, looked at short and long alleles of the gene 5-HTTLPR, which is involved in the regulation of serotonin, a neurotransmitter implicated in depression and anxiety.
An allele is a variant of a gene. Each gene has two alleles; humans inherit one each from mother and father.

Early research suggested that the short alleles predicted negative outcomes, such as depression, anxiety and substance abuse. People with short alleles were found to have higher negative emotions than those with long alleles.

But latest study adds to the evidence suggesting that people with short alleles also may be more sensitive to the emotional highs of life.

Amplifying emotions

Having the short allele is not risky,” says Haase, an assistant professor in the Human Development and Social Policy programme at the Northwestern’s School of Education and Social Policy. “Instead, the short allele amplifies emotional reactions to both good and bad environments.”