Forget about the sanctity of the human family or its sticky glue of love. If you’re a Trump, the institution is a convenient mechanism for ensuring inheritance, whether of gilded financial assets or brazen moral defects. Trumps are branded merchandise, and their dynastic DNA is a double helix of greed, graft and feuding malice.

Since numbers on ledgers are what matter to this mercenary dynasty, they advance arithmetically. In All in the Family, the last in a series of Fred Trumps identifies his great-grandfather – who absconded from Germany to avoid military service and founded a property empire by establishing a chain of brothels in Canada – as Fred Zero. His son Fred I, a rack-renting landlord in the New York suburbs, then begat Fred II, who defied the family by preferring a career as an airline pilot; then, after being reduced to a “second-tier Trump”, he drank himself to an early death, which made his younger brother Donald the heir apparent. Fred III, the author of this memoir, aspires to be “a different kind of Trump” but coyly trades on his tainted surname, describing himself on LinkedIn as “a third-generation member of a prominent New York real estate family”.

Trumpism consists, as Fred III puts it, of “name promotion”. Fred I advertised the homes he built by anchoring a yacht emblazoned with Trump signs off Coney Island on summer weekends. The logo has since been affixed to hotels, golf clubs, a failed airline, a dodgy university and several bankrupt casinos; it currently sells Bibles, high-top sneakers that yell “FIGHT FIGHT FIGHT” and a Victory cologne that purports to waft out the intimate essence of Donald.

What Fred III calls the “T-word” – almost as odious as the forbidden N-word, which he remembers Donald using when enraged by vandals who damaged his car – undergoes some slick mutations in the course of this chronicle. Fred Zero was born Friedrich Drumpf, which sounds like a belch or sneeze. Anglicised, the surname evokes trump cards and trumped-up accusations, a better match for the family’s ruthlessly competitive creed. Fred I’s middle name was Christ, rhyming with mist, which he derived from his German mother. But he worried that this might repel the Jewish tenants in his New York apartment blocks, so he dropped the “h” and called himself Crist instead. Fred III adopted the new spelling when he bizarrely christened his first son Cristopher; there would be no Fred IV, he decided, because “it was time to stop counting”.

The other Trumps remained at their adding machines, policing the succession. Donald’s sister, Maryanne – a judge who retired from the bench after a charge of misconduct, foiling his whimsical scheme to appoint her to the supreme court – complained because Fred III jumped the queue by producing Cristopher: according to her dotty theory of primogeniture, her own son, Fred I’s oldest grandchild, had the right to marry and procreate first. Then when Donald’s creditors threatened to foreclose on his debts during the 1990s, Maryanne and the other siblings produced a will altered by the already senile Fred I that disinherited Fred II’s offspring and cruelly cut off the medical insurance for Fred III’s severely disabled son William.

Fred III and his sister, Mary, sued to claw back a portion of the spoils to which they felt entitled. Mary, a trained psychologist, additionally declared war on the family in her book Too Much and Never Enough, published as a spoiler during Donald’s re-election campaign in 2020; in it, incensed by his mismanagement of the pandemic, she accuses him of “mass murder”. Her brother’s charges against their uncle are milder. Anxious to maintain a semblance of peace, Fred III reminiscences fondly about his access to the Oval Office and takes pride in his complimentary membership of a Trump golf club. The family’s handed-down anecdotes about Donald’s bratty behaviour amount, as Fred III sees it, to little more than “stupid kid stuff”: hyper-aggressive and liable to tantrums, he delighted in “the pain he hoped he had caused” by stealing toys from other children or hurling an eraser at a teacher he disliked. That might sound trivial, but these infantile urges still activate the old man who itches to regain power and they will be converted into vengeful authoritarian policies if he is re-elected.

Despite a settlement, the financial dispute with the aunts and uncles continues to rankle. For the Trumps, Fred III realises: “Blood only went so far – as far as the dollar signs.” Arguing about his grandfather’s will, he defends the protocols of “multigenerational wealth”, but that very terminology splices together genetic and economic heritage. As he ought to know, families pass on congenital failings as well as stocks and shares. His father once told him that he had “inherited a bad gene” and warned him to be careful about drinking; Fred III admits to having had his own foreordained struggle with alcoholism.

Donald, like Hitler, trusts in eugenics. At a recent rally in Minnesota, he promoted himself as a pure-bred product of “the racehorse theory”, and he fancies that his genes make him “a very stable genius”. His apostles agree. He recovered from Covid, according to the self-styled Maga life coach Brenden Dilley, because “he’s got God-tier genetics, top fucking one percentile genetics, right?” This insane conceit explains Donald’s spasm of disgust when Fred III tells him that William’s affliction is “some kind of genetic thing”. “Not in our family,” Donald replies with a snort, “there’s nothing wrong with our genes!”

The most lethal moment in the book occurs when Donald helpfully suggests that Fred III, rather than spending money on William’s care, should “just let him die and move down to Florida”. The advice comes from a remote-control executioner: after the death of the Iraqi terrorist Abu Bakr al-Baghdadi, Fred III listens to Donald exultantly telling the king of Jordan on the phone: “I killed him, I killed him like a dog.” What shocks me most, reading the exchange about William, is the casual logic of the follow-up. Why Florida? It’s Donald’s home, now that he is such a pariah in New York, and he commends it to his nephew as a moral Bermuda Triangle, a swamp for human alligators.

Fred III makes a final attempt to redeem his tarnished lineage by citing “something that William inherited from our family”. No, this is not a trust fund; it is the young man’s “heart-melting blue eyes”, his only means of communicating with the world. It’s a nice try, but a harsher truth is proclaimed by the book’s epigraph from The Godfather, which quotes Michael, soon to be installed as mob boss, when he shrugs that the gangsterism of the Corleones is “not personal, it’s strictly business”. Donald, who customarily deflects condemnation by projecting it on to others, used to rant about “the Biden crime family”; indirectly exposing the self-disgust that skulks behind his self-love, he was of course describing the vicious, venal conduct of his own clan.