No, I do not deny that this is made up but you are citing research, where is that research? You are writing an article in Canada based on Canadian laws with a Canadian perspective, please show the statistics that show this in that Canadian context.
I do not know of any 3 year old children in Canada that have shot their sibling with a loaded handgun in the night stand but I do know of this from the US and nobody was considered criminally responsible, it was considered an accident.
Lock up your guns and do not leave the keys accessible and nobody can shoot anyone with them, period.