Adrenarche and Puppy Love at Reinhardt

When did I have my first crush?

Dang if I can remember, but according to a hormone researcher at Univ. of Chicago, Martha McClintock, nearly everyone, male or female, when interviewed at a young age, reports having a first crush at age 10, in the fourth grade, well before testosterone or estrogen have reached adolescent levels for nearly all children. At around ten, children do have an early rush of androgens produced by the pituitary gland and enter the stage of adrenarche.

At 15, why did I fall in love so quickly while jumping on the trampoline with a girl I had previously been unattracted to?

From The Primal Teen by Barbara Strauch:

[Arthur Aron's] research has repeatedly shown that people fall in love more readily if they're already in a physically aroused state. That doesn't mean only a sexually aroused state, but any activity that gets the blood running high. For instance, two people who meet in a scary place, like on a high suspension bridge, or who think they're going to get an electric shock in a lab experiment, or who've been running on a treadmill . . ., are more likely to become attracted to one another.