If people around you immediately burst into laughter after a humorous moment, while you barely manage to crack a smile, this could be due to their genes, revealed a new study. The researchers demonstrated that people 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.
An allele is a gene variant. Each gene has two alleles; humans inherit one allele from their mother and one from the father. Study author, Claudia Haase from Northwestern University in the US, said, "The short allele amplifies emotional reactions to both good and bad environments."
The study combined results from three experiments from different Berkeley labs. In the first experiment, young adults were shown cartoon films. In the second, young, middle-aged and older adults watched a subtly amusing clip from the film 'Strangers in Paradise'. The third experiment asked middle-aged and older spouses to discuss an area of disagreement in their marriage.
The researchers videotaped the volunteers during the experiments. Overall, 336 study participants were included in the final analysis. The scientists collected saliva samples from the volunteers to analyze the 5-HTTLPR gene. The data from these three experiments combined indicated that people with the short allele of 5-HTTLPR showed greater positive emotional expressions. Those with the short allele displayed greater genuine smiling and laughing than people with the long allele.
The study is published in Emotion.