Guitar was my chosen instrument because there was one in the house.
Never had a piano or violin or anything else I might try, but my elder brother had a guitar, and I'd seen this cool kid at school playing one (although, looking back, it had to be the crappiest, most beat-up nylon stringer imaginable) and I thought, "That's the very thing for me!!"
Sadly the "cool kid at school" featured in a recent "Obit" thread and reminded me how I ended up being a guitarist.