I guess everyone develops conditioned responses which provoke sexual desires. Mine began with spanking.
My first response to an arousing stimulus was spanking. I saw a little girl spanked by her mother and had my first erection at about six. I had no idea of sex at the time, but every time after this when I was spanked or when I heard or saw another kid spanked, my penis hardened. I had a rather full understanding of sex about the age of 9 when I began masturbating. An older boy was my mentor, he always used vaseline when he masturbated, so I naturally did the same. After that beginning, every time I smelled vaseline, I could not resist the urge to jack off. I added soaps, shampoos, cold cream, and olive oil to my list of lubes, so their odors produced the same effect as spanking and vaseline. I began to ejaculate at 13 which resulted in the addition of the odor of semen to my list. Soon after my first ejaculation, a friend and I began jacking together at his house after school very day. So both of us became addicted to the view of the other nude jacking his lube covered peter as another fetish. We usually got in two jackings at his house, and I did 2 or 3 more a home every school day.