Dominic Lawson: It's only right the elder brother wins

The attractive side of the male sibling relationship, at its best, is that it can survive brutal competition. Whereas the relationship between a man and his wife is dissolvable

There is something about the contest for the leadership of the Labour Party that makes me want to cover my eyes – and it's not the vapidity of the debates. No, the cringe-making element consists in its coming down to a straight fight between two brothers. To be precise, what discomfits me is the prospect of four-years younger Ed beating big brother David.

There is no logic in this visceral reaction. Once you are in your 40s, as the two Milibands are, four years' seniority should be neither here nor there. Besides, any individual is always the most significant character in his own life's script; if Ed M feels that he would be a better leader of the Labour Party than his brother, why shouldn't he stand?

As the eldest of several siblings, I am inevitably predisposed to sympathise with David M's predicament. Doubtless there are many younger brothers across the land welcoming Ed's importunity. Still, it does break with convention in such matters. The Kennedy brothers took turns to stand for the Presidency, strictly according to their age. Similarly, George W Bush got the nod from his terrifying mother Barbara to run for the Presidency ahead of younger brother Jeb; that might not have been in the national interest, but it suited the Bush clan.

Then, in the Rome of two millennia earlier, there were the brothers Gracchi, whose equally dominating mother Cornelia Africana ensured that they ran for high office in succession, rather than in competition. Both were assassinated as a direct result of their political ambitions – but at least they each had a go as Tribune.

It is said that David Miliband's supporters had urged Ed to "wait his turn" and that this reflected the elder brother's own view; but if there is one thing the whole Blair/Brown feud should have taught the Labour Party, it is that it is better to have an open contest than to set up a quasi-monarchy with the succession arranged in advance by some sort of private deal. Moreover, while David Miliband may seem arrogant in manner, he is mercifully free of Gordon Brown's all-consuming conviction that the leadership of the Labour party was his by right: if he should lose to his younger brother, he is absolutely not the sort of person to spend the next decade in a miasma of vengeful fury.

On BBC Radio's World At One yesterday David Miliband insisted: "There's only one other candidate in this contest that I love, and that will come through strong." That might make some want to throw up, but I happen to think it was sincere – though it would not convince the Times columnist Giles Coren, who regarded the idea of two siblings competing for the same job as a mark of insanity.

Giles gave a charming account of his relationship with sister Victoria Coren, in which each takes great trouble to avoid competing directly with the other, though both are newspaper columnists. He contrasted this with the alleged sibling feuds of such pairs as the journalists Peter and Christopher Hitchens, the actresses Joan Fontaine and Olivia de Havilland, and the novelists AS Byatt and Margaret Drabble.

Perhaps one lesson from that is not to compete directly with your sibling in professional life; but there is another point, apparently not thought significant by Coren. All those feuds are between siblings of the same sex. It is a psychological commonplace that the rivalries between siblings tend to be much more intense when both are women, and – even more so – when they are both men. The ancient Greek playwrights, from whom Sigmund Freud derived much inspiration, not to mention the Bible, give chapter and verse: but these are merely the literary manifestations of eternal human nature.

Modern psychiatry doggedly continues to track the same phenomenon. Thus Professor Deborah Gold observed of her field study into sibling relationships: "The thing that rides through with brothers that doesn't come across in our [other] sibling pairs is this notion of parental and societal comparison. Somehow, with boys, it seems far more natural to compare them, especially more than with sister/brother pairs ... and this comparison appears to continue from school to college to the workplace."

I grew up in a household with three younger siblings – but all female. True to Professor Gold's observations, there were never any parental comparisons drawn between my achievements (or the lack of them) and those of my sisters. That certainly makes things much easier later on. A few nights ago, at a dinner party, I was introduced by the host to another of his guests as "Dominic, better known as the brother of Nigella". If Nigella, my junior by three years, were a bloke – which admittedly is hard to imagine – my response to such an identification would probably have been juddering rage. As it was, I merely found it amusing, which was presumably the intention.

Another form of intimate rivalry has affected the struggle for the Labour leadership. Many party members had wanted Yvette Cooper to run, instead of her husband Ed Balls. Cooper furiously rejected David Cameron's claim that Balls had "stopped [her] from standing" and insisted that: "Ed said he'd back me and stand aside if I wanted to run." She added that her reasons for not standing were nothing to do with deference to her husband, and everything to do with having four young children. That seems admirable; but it also illustrates the primordial fact that a woman, even one who thinks of herself as feminist, is more likely to find reasons for putting her own career second.

In Yvette Cooper's case, I'm sure it was all to do with her duties as a mother, as she asserts: but there is a further sense in which women are more likely to be sensitive about competing directly with men that they love – whether husbands or brothers – than vice versa.

One might illustrate this by the hypothesis that David Miliband, instead of having a younger brother Ed, had a younger sister Edwina. Would Edwina Miliband, loving her big brother as much as she does, and knowing that he was the favourite to become the next leader of the Labour Party, have decided to try to thwart his ambition in order to pursue her own, in direct public competition?

The attractive side of the much more unyielding male sibling relationship, at its best, is that it can survive the most brutal competition. Whereas the relationship between a man and his wife is dissolvable by circumstance and confrontation, there is no equivalent to divorce among siblings.

In the current issue of the Wisden Cricketer, the England bowler Graeme Swann describes how, playing for Northamptonshire, he ended his elder brother Alec's last innings as a county cricketer. After that game, six years ago, Lancashire released Alec Swann from his contract. He hasn't played professionally since. Asked if he regretted his role in his brother's debacle, Graeme Swann said "I do a bit", but then added, with the complete unsentimentality of the professional sportsman: "Everything fell into place for me and they didn't for Alec. That's just the way it goes."

Ed Miliband could reasonably take much the same view if he were to seize the glittering prize ahead of his elder brother. Still, it would be horrible to watch.