Rebecca Tyrrel: Mel Gibson's defenders recollect his rare gift for simulating fart noises'

Who knew that Mel Gibson has a horseshoe kidney? This congenital disorder affects about 1 in 400 people whose two kidneys are melded together into one giant organ. The extent to which this may explain why Gibson is such a gigantic organ himself is not clear. While side effects can include kidney stones, infections and tumours, there is no evidence that it heightens the risk of misogyny, homophobia, racism or anti-Semitism. Gibson is the only known super-kidney celeb on the planet, and it would be irresponsible to draw conclusions from a study group of one.

But what a one he is. The American-born, Australian-bred, Oscar-winning director and actor recently excited the media when scriptwriter Joe Eszterhas, whom Gibson had hired to write a screenplay, accused him of aborting a film called The Maccabees because "he hates Jews". Why Eszterhas took the job, having in 2008 accused Gibson as having "the mindset of Hitler" is as confusing as to why Gibson offered it to him.

The list of the Mad Max maniac's verbal outrages deserve a six-volume work, but a few are especially memorable. He refers to Jews as "oven-dodgers"; he once screamed at his former lover: "you look like a fucking bitch in heat... and if you get raped by a pack of niggers it will be your fault". His thoughts on homosexuality include the pithy: "They take it up the ass. This," (he went on, pointing to his own bottom) "is only for taking a shit." His defenders in Hollywood, who fondly recollect a love of practical jokes that includes a rare gift for simulating fart noises, are so bewildered they have taken to blaming his far-rightness on his genes.

Mel's father, Hutton (Red) Gibson, is a Holocaust-denier who regards Holocaust museums as a gimmick, and believes that burning heretics is "an act of charity".

Whether Gibson's trenchant opinions can be sourced to his genes belongs to the ancient nature vs nurture debate, but his own reputation as a pioneering medical researcher lies elsewhere. When arrested for drunk driving in 2006, he gallantly enquired of a woman sergeant: "What do you think you're looking at, sugar tits?"

Mel Gibson will be remembered, among much else, as the first person to identify a disorder – now known in Harley Street as Saccharine Breast Syndrome – at least as rare and exotic as the horseshoe kidney.