That's improable unless you have some kind of disorder (my apologizes if you do). Children should experience all kinds of emotions by age of two or three. Babies do exhibit jealousy very early on. Pouting comes with some degrees of anger, and one is generally considred too old for that by the age of ten. Most people don't remember anything from before they were five, and much of their childhood memories up to ten are usually diluted and hazy with time, and false memories so you may not remember being upset about something, like not getting a cookie at the age of four.
Did your parents tell you that you didn't show anger until you were eleven or are you just making a statement from what your memories tell you? Memories can play tricks on you years down the road.
Oh, believe me, I know how unreliable memories can be.

But truthfully, as far as I know, I did not experience anger and aggressive feelings towards another until I was 11 or 12. Frustration, annoyance, even stress: I felt these like anyone else, and I threw a tantrum once or twice as a very young child when my selfish frustrations overflowed, but anger? No. Jealousy, upset and those other things you mention were of course experienced, but the emotion of anger was not present.
I know it sounds improbable, and I'm not saying 100% I'm not mistaken, but I really believe this and I'm wondering if anyone can support it, or if there's some other explanation.
Well, alright, now I read why you're asking. Believe me, if you've experienced annoyance, jealousy, frustration, then you've experienced anger. Anger plays into all of those. You're normal. You may not get as angry as others but you have experienced anger.
Also, reading one of your later posts, those emotions don't preclude anger. They're build on the same foundation. You do experience anger. You are just giving anger a super strict definition so you can rule things out and say you hadn't experienced.
Alright, I've read yet more of this thread and will tack on additional thoughts. I see what's going on here. Basically, at around 12 someone really pissed you off and you acted violently. You were ashamed and now trying to justify it somehow. There are 2 most likely scenarios. Both straight forward.
1) You simply did not experience anything prior to that incident that pissed you off that much. No prior negative stimulus of that magnitude. You got angry before but it was dwarfed by this incident. You thought you were in control before but it was more due to a lack of exposure. It's a life experience thing.
2) You keep things bottled up. You experience anger but you keep it underwraps. So much so that you don't think that you even experience anger (although you clearly do). You give it such a convoluted definition to continue the illusion that you don't experience anger. However, one extreme incidents builds up so much pent up anger that pressure causes it to burst out in an act of violence.
I don't know which it is. It could be a mix of both. I'm leaning towards #2 based on your comments in this thread. If you think you haven't experienced anger, you are mistaken. Instead, it seems like you're repressing it and even redefining anger to maintain the pretense that you don't experience it. That's my guess since you asked.
Mr Awe