I am not sure when or how the awareness of gender differences creeps in but I think for some of us it spawned as early as the 3rd grade. One cant really point at a particular person or situation as responsible for this event but it does happen organically. My first memory is of how in 3rd grade accidentally bumping into a boy in the presence of another girl would trigger the "boy touch" offense. Yes, it was considered repulsive and was to be passed onto another girl ASAP, but there was a catch, you could only pass it onto a girl who was unaware and it would go on and on until the end of the day, it was our own Viral phenomenon during the dark ages. Until the transfer was completed (or until the affected had opened her lunchbox with her Amma's famous chutney powder coated idlis) she would be ostracized. I particularly remember the incident where I had brought this fancy pencil to school and upon a girl's challenge an annoying boy had picked it up and kissed