Depending on his age he might be trying to see how you react to it. But then again, I wanted to be a forensic pathologist, hairstylist, zoo keeper, marriage counsler, storm chaser, nun, and join the Navy. Not in that order but I would come up with off the wall things that I was serious about. My mom took me to a nun convention, bought me books on forensic pathology, gave me a number to a therapist to ask questions about marriage counseling, and I lost 100lbs and took a pre-ASVAB test to join the Navy. I currently finished cosmetology school to pursue a career as a hairstylist. So all I can say is, I had no idea what I wanted to do, I was constantly finding things I was very serious about, but I also know had my mom say you shouldnt do that, it would of subconciously make me more interested in doing it because I would of felt like it was a good choice and I would want to prove to her I know what's good for myself. Anyways. She really made it impossible to choose because she supported everything. Maybe she knew what the outcome would be. I don't know. I know this isnt an answer, but I hope it helps you find a solution to your dilemma.
My life xpierence as a depressed mildy OCD child/teenager with ADHD.