Perhaps the easiest way to start an argument online is to post a video of a mother raising her child. Within minutes, strangers will debate in the comments whether she is attentive enough, strict enough, patient enough or present enough, with some calling her irresponsible and others saying she’s controlling. Online and offline, motherhood has started to resemble a real-life Truman Show – a performance carried out under constant observation, where strangers across the country appoint themselves judge and jury.