I don't have a kid who plays.. Nor do I have a kid.. But I have a father and uncle who both play.. And I know where their mess of stuff is going to end up because no one else plays. My nephew though.. Should he ever end up playing.. He'll end up with 3x the mess.
I'm a guitarist (obviously) and have provided my son (now 7) with a shortscale electric, an acoustic and a little Roland practice amp. The result? He's an absolute machine on drums! Seriously, he goes to my workspace/studio almost daily and lets it rip. Very, very good. My only contributions have been to jam with him, remind him to keep it steady (over flashy) and open access to my drummer's drums (haha).
My daughter is 8 and she has a Mini Strat. She messes around with it from time to time, but like everything else there is coming a time when she will throw herself into it for a few weeks or months. I hope to get her interested at that time.
My wife plays the bass and every once in awhile I get her to play with me. It is fun when it happens.
My now 14 year old expressed interest 3 years ago. After outgrowing a half size strat I took him to nstuffmusic and he picked out a fender MIM tele. I tried to teach him for a few months to no avail. Then I sent him up with lessons with my old guitar teacher, he took 3 lessons, never practiced and lost interest. I guess naming him after Stevie Ray was wrong. He'd rather waste his day on XBox. Although he does listen to Trucks, Clapton and Lang...he still listens to Daughtry and Shinedown. I guess I may have expected too much.
My son turns one next month and one of his favorite toys is a plastic guitar that has buttons and a whammy bar that makes sounds. Pushes it all over the house and does his best Pete Townshend smash! He also gets mesmerized and stares when my brother or I are playing real guitars. I hope these are good signs that he'll want to learn when he is older!
My sons not only play, but we are in a blues band together! My oldest son is 33 and plays drums, my youngest son is 26 and plays bass and guitar. They are both great at it. We play the summer blues festival circuit and have played at Buddy Guys and such. It is a decent band I guess, and I have never had this much fun before!!!
My 23 yr. old son in an amazing musician. He records his own music playing and singing all the parts. A few years ago, his Christian band recorded 2 CD's which charted on Billboard. Yea he's a bit better musician than me and has been using most of my guitars,basses, pedals, and amps for a while now. Hopefully I'll grow up to be the musician he is.
My eldest took piano and voice lessons for several years and will still sing for herself. My youngest took piano and voice lessons for several years and will still sing when she feels the urge. She has also tinkered with the mandolin and ukulele but hasn't put in any serious time. Both in their 20s and too busy but I would love it if they got back into it.