Watch our webinar : Integrating Genetics and Psychology for Personal Development

“Say Cheese” , DNA said

How many times, when stuck into a party, wedding or gathering, you ended up hearing “Say Cheese” before hearing the click of your joyful friend’s camera ? I bet many times.

Laughter and smile is one of the most awesome human reactions. It’s the expression of pleasure, sociability, pure happiness and amusement. Both expressions are without doubt influenced by age, culture, gender, education, etc. But what about DNA? Can genetics affect our reactivity to humorous situations or funny things ? Can DNA predict our potential to laugh or smile?  This is the topic of today’s post ;).

Paper Title : Short alleles, Bigger Smiles? The Effect of 5-HTTLPR on Positive Emotional Expression

What it really means : How much you smile/laugh might be explained by your DNA.

One of the major biological influencer of emotions is the neurotransmitter Serotonin. As a neurotransmitter, serotonin is mainly found in the blood and the brain. It’s been shown that serotonin is the chemical responsible for maintaining the mood balance. And it’s well documented that low levels of serotonin are usually correlated with depression. One regulator of the serotonin effect in the body is the serotonin transporter 5-HTT, which removes serotonin released into the synaptic cleft. This transporter is encoded by a single gene (SLC6A4) which has been extensively studied. It’s been shown that the expression of this transporter can be influenced by small mutations (SNPs) found in the polymorphic region (5-HTTLPR). In other words, some mutations can affect the amounts of this transporter, leading to different levels of serotonin perception. And more or less serotonin means different mood states.

In this paper, the authors wondered about the possibility that these tiny mutations in the serotonin transporter can be linked to smile and laughter. To test that, the authors did three studies with independent human samples. Study 1 : Examined young adults watching still cartoons. Study 2 : Examined young, middle-aged and older adults watching a thematically ambiguous yet subtly amusing film clip. Study 3: Examined middle-aged and older spouses discussing an area of martial conflict ( that typically produces both positives and negative emotions). In all studies, a DNA test has been done to analyse the serotonin transporter gene and emotional reactivity (smile and laughter) were followed using a movies and bioinformatic analyses.

Results show that the short allele of 5-HTTLPR ( small mutation in the serotonin transporter) can predict higher emotional reactivity. Basically that people with this mutation laugh and smile more easily. Such discovery merit more investigation examining other positive emotions such as enthusiasm or love.

“Always keep your smile, this is how i explain my long life” Jeanne Calment