Obviously, you don't start off making meals, but how old were you when you started helping, and how old were you when you were capable of preparing a meal?
To be honest, I can't recall what age I started, because I started really young, and I don't have a lot of date markers in my mind for each year. I can pretty much sort out what happened before my ninth birthday from what happened after, and what happened in grade school years as opposed to high school.
I'm darned sure I was doing a bit of cooking before my ninth birthday ... it was before that when I sliced my thumb while peeling apples for an apple pie, and I was doing a lot of helping with other peeling, cutting, stirring tasks. I peeled and sliced and diced a lot of carrots and onions and potatoes, that's for sure.
I was supervised at the stove at a very young age -- I can recall needing to stand on a kitchen chair to be able to melt butter in a tiny pot we used for that task.
For some reason, the oven wasn't deemed as dangerous as the stove, and I baked a whole lot of cakes, mostly from boxed mixes, but also some oddball recipes. Cookies too. Mom didn't like baking much, so I was on my own for a lot of that.
I also remember the first full meal that I made was for a girl scout badge, and I was disappointed that it wasn't more complicated. So I was probably under 12 at the time.