I'm pretty sure I was about 4 years old, but positive that I wasn't more than 5 1/2.
My Dad got hurt at work in the mines and sold a 38 special snubnose to help cover some of the bills. When the buyer wanted to try it, I asked if I could shoot it too, and Dad let me stand in front of him and he helped support the pistol as I racked off a round toward a tree stump.
I can remember trying to do everything exactly the way he told me. And I remember that (then) it was very very loud to me but it was still love at first shot. I declared that I hit the tree stump, but was probably more wishful thinking than anything.
Afterwards, my Uncle Bill let me use his old Red Ryder BB gun everytime I went up to my Grandparents house (which was a lot) as long as I provided the BB's and didn't shoot at the windows or chickens, and after probably a million BB's later that summer I graduated to my Great Grandfathers ORIGINAL 1894 Marlin in 25-20 in my Grandmothers back yard with her at my side showing me how it works.
Needless to say, I have been around guns all my life and was taught from very early on the responsibility it takes to be safe with them, and care for them, and how to use them.
Shooting guns came natural to me.