Myself...my parents didn't ride and didn't like motorcycles.
Back when I bought my first bike...a 1988 Kaw Ninja 600R I didn't even know if I'd make it home alive since it was 5:00 pm in rush hour traffic when I picked it up. I got it home just fine and then wrecked it 4 days later after locking up the front brake and collecting some asphalt rash.
I finally got the hang of it and have now owned probably 10 bikes and have been riding on and off for 20 years or so.
My older brother taught himself as well and several years later after joining the police department he ended up as a motorcycle cop so he did have to get actual training there.
After a few years of this he got promoted and was in charge of the motorcycle squad for the Raleigh, NC police dept. for a few years. He's now retired.