So, we are a factor of 17-81 more inclined to respond with a smile than to initiate a smile, females are a factor of 2.7-10.8 more inclined than males to be targets of a smile, and men smile more often, except that men are a bit less inclined to initiate a smile to a woman than is a woman to another woman.
Anyone in mood to do field observations, to check if actual behavior matches these poll response claims?