If you don't count the home made motorized-bicycle stage, and want to consider only actual motorcycles, I started riding at age 15 (in 1968), rode on-and-off til age 21 (1974), and re-started at age 51 (2004).
My first was a "borrowed" Honda 50 walk-thru. The older brother of a friend had gone off to college, and foolishly left the Honda where we could get to it. No license, registration, insurance etc. - we just got on and rode it. Thought we were Hell's Angels.
First "owned" bike was a Ducati Falcon Sport 80 (co-owned with another buddy). Small and smoky, but fun. I still have pictures of us trying unsuccessfully to kick-start that POS.
In college I had the worst Triumph ever made, a 1965 TR6R. It left me stranded many, many times. Worst of all, I never impressed anyone when I rode it (important at that age).
I did not ride after college, can not say why.
My next was in '04, a 1979 Yamaha XS650 Special. Fun bike, cheap, easy to get parts, terrible charging system.
After that, a 2004 Triumph Bonneville. Wonderful motorcycle.
This year I upgraded to a BMW K1200S. Two weeks ago, I got my first motorcycle speeding ticket. Ever. Fun, fun, fun, but way too exciting when you get a sudden flat front tire at 60+ MPH.
My wife is nervous about me riding but has been a good sport. My younger sister is angry with me and refuses to discuss it. My 80-year-old mother does not need to know.