2 year olds might react by screaming and stamping, 4 year olds are much more controlled and devious. My daughter, when 2, would scream and bang her head on the floor. When 4, she was more than capable of finding something that could be used as a weapon and would wait for her little revenges.

And if a 4 year old can work the childproofed video, childproof locks, childproof safety gates, Transformer toys, digital camera or the many electronic toys available, they are more than capable of taking off the safety catch, especially if they have seen mummy or daddy do it. Do not underestimate the capabilities of a 4 year old child.

However, the 'accident' with the 15yr old, yes.. at 15 you should be capable of preventing such accidents. That one should be put down to lack of teaching, lack of respect for weaponry and sheer blind stupidity.

LTS