When we meet new people, we assess their character by watching their gestures and facial expressions. Now a study in the Proceedings of the National Academy of Sciences USA suggests that those nonverbal cues are communicating the presence of a specific form of a gene that makes us more or less responsive to others’ needs.

The gene determines which type of receptor a person has for the hormone oxytocin. Oxytocin has been implicated in a variety of positive traits, such as trust, empathy and generosity. The hormone is detected by our body’s cells via their oxytocin receptors. In a past study, psychologist Sarina Rodrigues Saturn of Oregon State University and her collaborators found that people who have a certain variation of the receptor gene are more empathetic than those with the alternative form of the gene.