Yesterday, Rupert Murdoch descended from Mount Doom to issue one of his characteristically gnomic utterances via Twitter: "Prince Harry. Give him a break. He may be on the public payroll one way or another, but the public loves him, even to enjoy Las Vegas."

It was, perhaps a shade less characteristically, gallant of him to defend the prince from the approximately no people who have attacked him in the past few days, since the unleashing of his bottom on the world. The consensus – and it's interesting to notice how general it seems to be, crossing generation, social class and political party – is that Harry Windsor can do what he likes as long as all parties are consenting adults.

Harry isn't the only scion of a rigid dynasty who attracted attention last week for breaking the family rules. Giving the annual MacTaggart Lecture at the Edinburgh International Television Festival, Elisabeth Murdoch flagrantly contradicted every position her brother James took at the same event three years ago. Where James took the official News Corp line – BBC is hegemonic and evil, profit the only reliable guarantee of an independent media – Elisabeth more or less stroked Mark Thompson's beard while issuing horrified squeaks about "profit without purpose".

Her lecture attracted applause, but also much snark about her sincerity – was she trying to supplant James as heir apparent to the Murdoch empire? Was the whole thing imperially approved propaganda? So far, Rupert's tweets haven't given his views. What both episodes emphasise is a certain confusion about families – what we owe them, what they should do for us. During the past century, the tendency in Britain has been to reject family as the determining factor in our lives. Once it seemed natural that people's circumstances – social status, profession, where they lived – were dictated by their parents: the son defying paternal authority to do the "wrong" job or marry the "wrong" girl was a staple of fiction.

Now, we have a more limited vision of the duties parents and children owe one another. The child doing the job, marrying the person their parents expect, is an object of pity; we look askance at somebody still living at home after 25.

But still family values tug at us. We have trouble discarding our faith in the hereditary principle as a basis for the British constitution; recession and ludicrous house prices pull a generation towards their parents' back bedroom; and we're only interested in Harry and Elisabeth at all because of who their parents are. Harry's lack of regal propriety may titillate, the scorn Elisabeth pours on Murdoch mores may tweak our political antennae; but in the end, what makes the thrill is seeing a child in conflict with the family, the escape attempt that can never quite succeed.

Twitter: @RobertHanks