Don't remember when I watched porn for first time but I think it was around 6 or 7 years old. By accident at first if I remember corretly, which means I didn't know it was porn at that time (damn you google image xD)

Though the sex ed starts for first time when some people hits the puberty which means when you are around 11 or 12 years old while last year of primary school and first year of high school more. This time was more talk about relationships, STD:s, LGBT (much talk about this actually), protection etc.

Our country takes sex ed pretty serious. That's how I see it anyway. Also it happens depending on the teacher they could show us light porno (and this is not a joke)

For violence I think it's more self-control and how you have been raised. And pretty much as Cuda and Art already have said.