How deeply we gaze at happy faces depends on our genetic make up, reveals study led by an Indian-origin researcher.
Dr Bhismadev Chakrabarti at the University of Reading and Prof Simon Baron-Cohen at the University of Cambridge have found variations of the cannabinoid receptor (CNR1) gene that alter the amount of time people spend looking at happy faces.
They analyzed the DNA from 28 adult volunteers and tested (using a "gaze tracker") how long the volunteers looked at eyes and mouths of faces in video clips showing different emotions.
They found variations within two of the four polymorphisms (naturally occurring mutations) in CNR1 correlated with a longer gaze at happy faces but not with faces showing disgust.
Both of these genomic sites involved for happy faces were within part of the DNA which does not code for protein but instead may be involved in regulating protein production.
"This is the first study to have shown that how much we gaze at faces is influenced by our genetic make-up," said Chakrabarti.
"If replicated it has profound implications for our understanding of the drive to socialize, and in turn, the atypical use of gaze in autism," he added.
The study has been published in BioMed Central's open-access journal Molecular Autism.