As a little farm kid, I was always interested in the sick animals and medicine. That evolved into infectious disease. It's still a hobby. I'm careful not to talk about it much - I don't want the FBI thinking I'm trying to become a terrorist - but my friends know. The come to me for help on their research programs sometimes. I've even been published twice, despite a degree and working in a different field (law). Whether the hobby stays a hobby or becomes a career, it's nice to have a strong interest.
My aspie child adores robots, all kinds of robots. He also takes apart things to make robots out of them (well, he tries). I hope he continues to enjoy them as he grows up.
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Apologies if I sound judgmental, preachy, dictatorial, offensive or overly rigid. Constructive criticism via PM is welcome.