When people make this comment about Canada and the Geneva Conventions they are referring primarily to Canada's conduct in WW1 and WW2, and in particular their treatment of POWs (i.e. killing POWs). There may also be reference to events like Canadian soldiers switching cans of food thrown to German soldiers with explosives.

Canada has had other incidents, particularly in Somalia with the airborne, who were disbanded.

These are facts that can be discovered with a little research. The other things you mentioned are things that you may wish to associate with Canada, but unfortunately for you Canada's war crimes typically involve treatment of POWs and perfidy, not rape and 'smashing babies against trees'.

And associating Canada to the British Empire is a pretty hamfisted way to try to implicate Canada in the colonial and imperial adventures of the British Empire that spans centuries and predates her.