JUST RIGHT: Charlie Sheen and wife Denise Richards locked in a kiss. (AP/PTI)

London, Feb. 12 (Reuters): How people kiss, with a preference to turn the head either to the right or left, is a trait that is developed in the womb but probably lasts throughout life, a German psychologist has said.

Although they may not realise it, people turn to the same side before planting a kiss on the lips and twice as many people turn to the right.

“There could be one very early habit given to humans before birth which still influences our behaviour for the rest of our life and is visible in subtle habits during, for example, kissing,” said Onur Gunturkun of Ruhr University in Bochum Germany.

The preference for turning the head to the right is one of the earliest examples of behavioural asymmetry and scie-ntists suspect it influences sidedness, such as favouring the right foot, ear, eye, or kissing side, for life.

To test the theory, Gunturkun secretly observed 124 kisses of couples in international airports in the US, Germany and Turkey. He found a ratio of about 2-1 turned their heads to the right.

Gunturkun said the results of the study, which are reported in the science journal Nature, indicate that adults have a head-turning bias towards the right side, just like embryos and newborns.

“The preference to turn the head to their right... prevails through their whole life so it could be the key agent to induce all other asymmetries our brain has,” he said in an interview.

Auguste Rodin’s famous sculpture “The Kiss” seems to support Gunturkun’s finding as the couple are both turning their heads to the right.