The Brothers Obama – who's the role model now?

Barack and George were saint and sinner. But as the President's term of office closes, they appear to be exchanging roles

What if they had elected George Hussein Obama instead of his big brother Barack as president of the world's most powerful nation four years ago? Nearly 8,000 miles in geography and 20 years in age separate the two men. They share the same father but have different mothers.

By the accident of birth, Barack Hussein Obama was born in Hawaii to his father's second wife. George was born in Kenya in their father's fourth marriage. The two sons have only met twice. One is President of the United States; the other is dubbed by his neighbours president of one of the world's most notorious slums, Huruma, in Nairobi. One is the apotheosis of the American dream, the other of the African nightmare.

When George Obama first came into public view in 2008, he was seen, to use his own words, as the "black sheep" of the family. His was a cautionary tale of how things could have gone wrong in his big brother's life. Their absentee father played virtually no part in the upbringing of either boy. Both had stable stepfathers; both did well at school; both experimented with drugs and joined gangs as teenagers. But Barack Obama was soon back on the straight and narrow, where George, after his white aid worker stepfather vanished one day, went off the rails. He was thrown out of his smart boarding school, where he played rugby and was a star pupil, for smoking marijuana. He soon began hanging out in chang'aa dens, drinking spirits illicitly distilled from fermented maize spiked with methanol.

George became estranged from his despairing mother who moved to the United States, leaving him behind. He lived rough on the streets of the fast and angry city for 10 years. He became a bad-ass gangster, a one-man crime wave, pickpocketing and hijacking matatu taxis. He was known as Obama the Mamba – Swahili for crocodile – for his ruthless method of striking first. As one of Nairobi's most notorious criminals, he indulged in the fantasy that he was a kind of Robin Hood; in reality, he was part of the city's increasingly vicious circle of injustice.

But in 2003 he was arrested for an attempted armed robbery that he denied committing. He spent nine months awaiting trial in one of Africa's vilest jails. But he emerged resolved to change and, by good fortune, fell for a neighbour's daughter in the slum's One Love youth group. It taught him there was a "magic" about the non-criminal community in Huruma and he began drawing slum kids into a garbage-recycling project as an alternative to a life of crime, drugs and prostitution. In 2006, he met his brother who was on a tour of East Africa, and pronounced the senator and Harvard lawyer "an inspiration". George continued coaching his youth football team, Huruma FC, which in 10 years got to the national soccer championship final. He had become the embodiment of his big brother's "Yes we can" philosophy.

The parallel careers of the Brothers Obama have been counterpointed in a powerful new play Obama – the Mamba by Kevin Fegan, which draws on books by the two brothers, and which opened here this month. George, who shares his brother's charisma, is given a excoriating speech in which, with dubious economics but potent emotion, he compares Africa's bribes with America's taxation – and asks how Kenyans can be called corrupt by Western politicians who claim for second homes they don't live in, or bankers who steal from pension funds, or financiers who screw chambermaids like they screw the Third World. All this in a rich world where people sleep in doorways and scavenge food from bins. The brothers, George's rhetorical rhapsody concludes, are: "Two sides of the same coin. Yin and yang. I am dark and you are light. I am Chuck Berry to your Elvis."

Yet the resonance this would have had in the last presidential election race rings hollow today. George may have enjoyed a trajectory from failure to success, but Barack's journey has been one from glorious hope to sour disappointment. He has kept open Guantanamo Bay, continued the war in Afghanistan and increased drone attacks that have killed thousands of innocents in Pakistan. He has preserved George Bush's tax cuts, decriminalised torture and prosecuted more whistleblowers than all previous presidents put together.

Some environmentalists, human rights activists and anti-Wall Street campaigners are so disillusioned that they have begun to argue against those Democrats who say that Obama is – contrasted with the opportunist Mitt Romney and his deeply conservative running mate Paul Ryan – at least the lesser of evils. "Lesser evilism" allows the Democrat establishment to take for granted their supporters on the left and to shift the party more and more to the right in search of support from the political centre. It produces increasingly unprincipled politicians and a two-party system that constantly narrows real choice.

The President's opponents claim that George, now 30, is once again frequenting the chang'aa joints in Huruma slum. But he looked contained enough in the play audience in Leicester and Manchester. Had Fegan written his play four years ago, Barack would have been the role model and George the emulator. Today, those roles might seem better reversed. And the lesser of evils might not be enough to secure big brother Barack a second term.