If he was actually smoking, drawing it into his lungs quite happily, like it is reported, then CLEARLY he had been doing it regularly for some time. I know for a fact that a non-smoker, having a puff, has a quite different reaction! (cough/choke/eyes popping/whatever ) You don't take a deep drag and blow it out!
Clearly he knew what he was doing. I don't buy for a second that she didn't know about it. Terrible if she did - but tbh, just as bad if somehow he had managed -at 3 to learn to smoke without her realising. I mean, come ON.
I am sure there will be posts defending her and urging us not to judge lest we be judged, and lots of angry faces at our terrible attitude towards a poor mother who may be , but fuck me, some things DESERVE judgement.