From 5 yrs old to 14, I was primarily trained on airguns. My dad and I shot his air rifle and then moved on to an air pistol. At 14, I shot his Marlin Model 60 (22lr), then a buddy's Ruger MkII (22lr). Interspersed in there were other handguns: Glock 17, Ruger GP100, Ruger SP101, etc...
My first handgun I bought was a 9mm. I never owned a 22lr pistol until just a year ago. I figured I needed to stop borrowing my dad's when I took a newbie out shooting.
So- I concur that a 22lr (or air) pistol is a GREAT one to start out on, but it doesn't have to be the first one "you" buy. If you're trained on a friend's/dad's/uncle's, you don't necessarily have to go out and buy your own. Go get what you want.
All this talk has reminded me that I've always wanted a full-size CZ 75 and a Kadet conversion to go with it. I'll see you guys later, I'm going to the gun store...