Quite honestly, from personal experience i can vouch for the half wit mutant theory. Always wanted to fly or make stuff (sophisticated paper planes, RC model planes, kites and so on) fly since i could think. Which of course lead to flying at the minimum legal age of 14 in glider planes and from there to the aim of being an air line pilot. Tried something else first (computer sciences) but it was kinda boring so i got my ATPL and enjoyed flying ever since.
To be honest, it helps that i only fly around 300 hours a year, that way i thoroughly enjoy every single day of flying at my job.