Donut and I both started out by learning to play the recorder at school. But "when I were a lad", recorders were still made of wood and had a nice sound to them. I think the modern plastic ones are crap, they do more harm than good, putting kids off music making for life.
My second instrument was the ukulele (which is tuned similarly to the top four strings of a guitar) and then I progressed to guitar, double bass (which is tuned similarly to the bottom four strings of a guitar), and finally bass guitar (which is tuned the same as a double bass).
Somewhere along the way I picked up some very rudimentary keyboard knowledge, but I can't actually play anything. I suppose I ought to learn, maybe have piano lessons.
Oh yes, and I learnt the violin for a bit too when I was a kid, but I've completely forgotten it.
And I also play the blues harp (oh, OK the mouth organ) and the kazoo!
So how did everyone else get started, or is the bass guitar your first instrument?