The popular UK television programme, “Who Do You Think You Are?”, would have a certain ironic resonance for Katrin Himmler. For she cannot escape knowing exactly who she is: the great-niece of Heinrich Himmler, head of Hitler’s SS and thus a byword for terror and mass murder during the Third Reich. If he had not committed suicide after his arrest in 1945 he would undoubtedly have been hanged at Nuremberg. His great-niece, born in 1967, wanted to change her name for many years, but researching her family’s hidden past for this book helped her to come to terms with her malign inheritance. She both wanted to know the truth yet feared “what might come to light”. By a further irony she now lives with an Israeli whose Polish grandparents had to hide from her great-uncle’s minions to avoid being sent to the death camps.

There were three Himmler brothers: Gebhard, Heinrich and Ernst, the author’s grandfather. He went missing, presumed dead, during the bombardment of Berlin in 1945, so she never knew him either. After the war, her father and other relations consciously distanced themselves from their Nazi associations; Katrin was brought up to believe that the family, apart from its one embarrassingly aberrant member, had been a-political and uninvolved. Her researches revealed a different story. Everyone was “complicit in maintaining the family myths,” she laments. Her grandmother, Paula, a milliner by trade, who kept up with old Nazi friends long after the war, “must have had to make great efforts not to know anything” of her brother-in-law’s activities.

In fact, Heinrich’s brothers joined the Nazi party even before Hitler became chancellor in 1933; there was no coercion and no reluctance. Heinrich gave his brothers, both qualified engineers and to whom he was close, a helping hand in their careers. They owed their prosperity to his influence. Not only this, but their parents, after initial worries that their middle son, who had studied agriculture, was taking time to establish himself in a respectable job, became enthusiastic Nazis, glad to have honoured places at party rallies and the use of an official car and driver. Like other Germans they had been deeply affected by the aftermath of World War I; they saw their savings drain away and their well-educated sons join the ranks of the unemployed. “Nothing prepared the German middle classes for Hitler so much as the inflation of 1919-23,” remarks the author.

So what kind of family produces a mass murderer? Answer: anyone’s family. Katrin Himmler’s book is not a study of Heinrich’s peculiar psychology, which has been written about many times; it is simply a compelling study of the particular society that produced him. The Himmlers were an unremarkable middle class household from Munich. Gebhard senior, keen on getting on and something of a social climber (he was proud of his acquaintanceship with the Bavarian royal family) became headmaster of the prominent Wittelsbacher Gymnasium; discipline, conscientiousness and above all respectability were his family’s values. He had a well-stocked library, was an able scholar of the classics and a cultivated man, so much so that a former pupil later asked despairingly, “Can the humanities not protect us from anything?” One is reminded that Reinhard Heydrich, close colleague and subordinate of Himmler’s, deeply instrumental in rounding up Czech Jews for the camps, was a proficient violinist and loved Mozart.

Heinrich, born in 1900 and looking neat, aloof and bespectacled in youthful photos, commented in his diary aged 14 that Russian prisoners of war “must breed like vermin.” He was something of a prig, though a cranky one; homeopathy, spiritualism and the occult replaced Catholicism as his creed in adult life. National Socialism, with its mixture of militarism and nationalism, fulfilled other, inchoate yearnings. As early as 1924 he was commenting that Hitler was “a truly great man” and his speeches “are magnificent examples of the German and Aryan spirit”. Appointed Reichsfuhrer SS in 1929, he turned a tiny bodyguard squad into a hugely successful elite corps of over 3,000 men within two years. Living with a mistress as well as a wife (though he was so busy he saw very little of either) he advocated institutional bigamy for the “racially pure” SS; he conceded that the first wife should be treated with respect and called the “Domina”.

Gebhard, the surviving brother, tried to portray Heinrich after the war as a “selfless, self-sacrificing servant of the regime”, saddened by the unpleasant tasks that destiny demanded he organise so efficiently – somewhat like Lewis Carroll’s Walrus and Carpenter, who wept salt tears over the oysters they gobbled up. His great-niece has no such illusions. Understandably, the writing proved a painful journey for her, with several anguished mental blockages along the way. Learning of her grandfather’s betrayal of a colleague to his brother, she admits “it took me six years finally to face up to this letter.”

As always with books of this kind, I ask myself: living in Germany during those times and under those circumstances, not a Jew and not very brave – what would I have done?

Francis Phillips writes from Bucks in the UK.