I did it....Totally backwards. Didn't have a bike as a kid. In my twenties, I decided to learn to ride a motorcycle. I bought a well-used Honda 90 and flogged it around a dirt/gravel circuit till I could keep it upright. Lost mucho skin from my shins.
Got so fond of motorcycling I took up motocross. Read somewhere that riding a bike was good training for MX, so I bought one. Took me about 10 minutes to get going.
After breaking bones, I gave up motocross and kept the bike.