The reason is not hard to find. With regard to their children's behaviour, politicians' motto tends to be: "There but for the grace of God go I." Whatever a parent's views, a teenager's behaviour is impossible to control.
The Conservatives know this as well as Labour. Three years ago the home of a minister responsible for drugs and policing was raided after a party held by his teenage son. While Michael Forsyth, then Home Office minister of state, was away on holiday, his 16-year-old son was caught by police at the gathering at which drugs were found.
Tabloid reports at the time said the teenager had "openly boasted of smoking cannabis, and held a boozy get-together at the house". The incident is instructive for two reasons. First, Mr Forsyth not only survived the incident, but his political career prospered when he was promoted to Cabinet rank as Secretary of State for Scotland.
More interesting still, when he took up that post - which included responsibility for drugs policy north of the border - Mr Forsyth was far from a hawk on the issue. Although from the right of the Tory party, Mr Forsyth floated the idea of a "fixed penalty system" for possession of cannabis, reducing the offence to the level of a speeding ticket. Only the opposition of Michael Howard, then Home Secretary, stopped such a reform north of the border.
A similar reform is unlikely to emerge from Mr Straw, who has gone out of his way to stress his hawkish stand in the battle against drugs. But the event has illustrated beyond any doubt that cannabis use is widespread, permeating even the households of respectable middle-class parents. Sir David Steel, former leader of the Liberals, knows this only too well because his son was convicted of growing cannabis. As one Tory ex-minister put it: "All those with kids know that you can't control aspects of their behaviour when they go out for an evening."
If anything, rebellion is probably more likely than not to manifest itself in the families of politicians. One close colleague of Mr Straw argued: "Jack will command sympathy among the public as a parent confronting very difficult personal circumstances in his family. Being Home Secretary adds not only to the stress on him but also to that on his family. You can imagine very difficult tensions within the family, with the son being ribbed about his dad telling young people they should observe curfews and be in bed early. You can understand how it happened."Reuse content