Men were about 15 times more likely to initiate kissing than women, and both partners showed a bias for turning their heads to the right.

Dr Rezaul Karim, from the department of psychology at the University of Dhaka, said: “This is the first study to show sex differences in the initiation of kissing, with males more likely to be the initiator, and also that the kiss initiators’ head-turning direction tends to modulate the head-turning direction in the kiss recipients.

“Based on our prior theoretical work, we are also able to make new hypotheses about the underlying neural basis for these behaviours.”