Thilo Sarrazin, who said claimants should have cold showers and spend €3.70 a day on food, has son living off state

No one has criticised the German welfare state as publicly as Thilo Sarrazin, the banker whose book on Germany's perceived demise has sold 1.2m copies in six months.

Sarrazin's controversial tome, Deutschland Schafft Sich Ab (Germany Is Making Itself Redundant), argued that Germany was going to the dogs – largely thanks to ill-educated, work-shy benefit claimants, especially foreigners, who were draining the nation's coffers and making the country stupider in the process.

What he failed to mention was that his own son was dependent on benefits and hadn't held down a job in quite some time.

This week, Richard Sarrazin, 30, broke cover to tell Bunte magazine – Germany's answer to Hello! – about his paradoxical existence as the son of a millionaire author living on the breadline.

Under the headline "I am the black sheep of the family", the 30-year-old came out with a string of comments sure to enrage his father, who as Berlin's finance senator and board member of the Bundesbank adopted a famously scathing attitude towards those in receipt of state help.

Sarrazin Sr once suggested benefit claimants should save money by having cold showers and not having the heating on, and said it was perfectly possible to eat a nutritious diet on just €3.76 (£3.20) per day. Germany made it too easy for those on welfare, he repeatedly claimed – a statement apparently backed up by his own flesh and blood this week.

"It's actually pretty good to just be unemployed and not be needed, because you can determine your own pace of life," Richard allegedly told Bunte this week, from what the magazine notes is his "well-heated" flat on the 14th floor of a tower block in Berlin.

It wasn't easy being Thilo's son, he moaned, saying he had problems meeting women because of his now-notorious surname. "I could only keep a girlfriend for so long before she found out who my father was," he said.

His dad had treated him unfairly, he claimed. "I am a scapegoat for my father, the black sheep of the family."