I'm not sure when I started using a sharp knife. My brother probably would have been handed one at a younger age than me, simply because of our temperaments. He was much more careful than I was.

I know we both helped in the kitchen at an early age. I insisted on having real ingredients to work with. I think if I had a child that wanted to use a knife, I'd also go for supervision of a sharp knife rather than a dull kid's knife.