What do you know about Sacha Baron Cohen? That he pioneered the now-tiresome catchphrase, 'Is it 'cos I is black?' That he wrestled nude with a hirsute, obese man and sang about throwing Jews down a well?

That he parachuted, naked-bum first, on to Eminem's mock-disgusted face at the MTV Movie Awards?

Well, you would be wrong. Baron Cohen would point out, splitting hairs-wise, that those were the respective actions of his comic creations, Ali G, Borat and Brüno, and not him. In fact, the 38-year-old has gone to great lengths to ensure the public usually only sees him in character, and very rarely as himself -- a quiet, politely-spoken, Cambridge-educated, middle-class Jewish father of one.

So just how did a boy of privilege, who at one time seemed destined for a career in academia or at the bar, end up trailblazing through the world of comedy with a succession of satirical personas that have offended as much as they've delighted, the latest of which, Brüno, is fielding charges that it perpetuates, rather than lampoons, homophobia?

Sacha Baron Cohen was born and raised in the affluent Hampstead Garden suburb in north London in 1971, the youngest of three boys (his brother Amnon runs a computer consultancy in Israel, while Erran is a musician who contributed to the Borat soundtrack).

His father Gerald, originally from Wales, made a considerable living from running a menswear shop, while his Israeli-born mum Daniella was a dance teacher.

Baron Cohen was quickly spotted to be a fiercely clever child. He went to the prestigious Haberdashers' Aske's Boys' School, where he met Dan Mazer, his long-time writing partner and producer. Baron Cohen later called the school a "factory of comedy", since past pupils have also included David Baddiel and Little Britain star Matt Lucas.

It was as a young schoolboy that Baron Cohen first discovered Peter Sellers, the actor and comedian who has been a life-long idol and inspiration for his own work.

"I think I was about seven when I saw the first Inspector Clouseau film and I really believed the character," he has said. "Then I started to see more and more of Sellers' films. He was this incredibly realistic actor who was also hilarious and who managed to bridge the gap between comedy and satire."

The Baron Cohens were an observant Jewish family and a teenage Sacha joined Habonim Dror, a progressive Zionist youth movement. This turned out to be a fateful turn of events, as it was in this group that he got his first taste for performing. He joined a breakdancing troup who provided the entertainment at his own Bar Mitzvah.

"Essentially, we were middle-class Jewish boys who were adopting this culture, which we thought was very cool," he told Rolling Stone in 2007. "That was sort of the origins of Ali G."

None of this detracted from his education, however. After spending a gap year picking avocados on the Rosh Hanikra kibbutz in Israel, Baron Cohen won a place at Christ's College in Cambridge, where he studied history, completing a dissertation on the subject of Jews who supported African-Americans in the civil rights movement in the US.

He kept up performing at university, joining the Footlights theatrical club and starring in productions of Fiddler on the Roof and My Fair Lady.

Baron Cohen wears his education lightly, but he has indicated that the lessons from history inform his outrageous and envelope-pushing approach to comedy and performing. As he explained in a recent interview: "I remember when I was at university reading this historian named Ian Kershaw, who wrote that, 'the path to Auschwitz was paved with indifference'.

"I know it's not very funny being a comedian talking about the Holocaust, but I think it's an interesting idea that not everyone in Germany had to be a raving anti-Semite. They just had to be apathetic."

After graduating, he set himself a deadline of five years to make it in showbusiness before settling for a proper job, most likely as a solicitor. Standing at 6ft 3ins, with striking dark good looks, Baron Cohen made some money as a model, before becoming the host of a teen chat show on a satellite channel.

In 1995, Baron Cohen moved on to a local cable channel in Slough, where he began developing a slew of comedy creations, including 'MC Jocelyn Cheadle-Hume', a proto-Ali G-style character who adopts a gangsta rapper persona despite being the white son of a bishop.

His break came in 1998 when he auditioned for Channel 4's The 11 O'Clock Show as an Albanian TV reporter that later evolved into Borat. The show's producer, Harry Thompson, was hugely impressed and challenged him to create a character that would be a satirical reporter on 'yoof issues'. Baron Cohen came up with Ali G, inspired by his own irritation with young white men who tried to mimic black street culture, and suddenly his comedy career was sent into orbit.

Ali G landed his own show, winning Baron Cohen two Bafta awards, selling millions in DVDs, prompting imitations from everyone from Prince William to Richard Madeley, and even appearing in Madonna's video for Music.

The character rankled with a lot of people; Baron Cohen was accused simultaneously of being both racist and a self-hating Jew. It was the strength of this reaction that encouraged Baron Cohen to draw a strict line between the real him and his professional creations. Therefore, he rarely does interviews as Sacha Baron Cohen, preferring instead to appear on television and on junkets as his comedic characters.

In one of the rare interviews he has done as himself, Baron Cohen said: "I am a very private person and to reconcile that with being famous is a very hard thing." This doesn't mean that he is a dysfunctional recluse, however, unlike his hero Peter Sellers who once remarked: "There is no me. I do not exist."

Baron Cohen is happily engaged to Australian actress Isla Fisher, whose own career has been considerably boosted in the past six months thanks to her effortlessly charming performance in the otherwise-forgettable Confessions of a Shopaholic. The couple have a two-year-old daughter, Olive, and divide their time between London and LA (there are reports that the family will be relocating to Ireland later this summer if Fisher signs on for the action comedy Your Highness, which is slated to be filmed here).

As for Baron Cohen, it remains to be seen what his next career step will be. He admits himself that characters such as Borat and Brüno are victims of their own success and so cannot be repeated. Even the filming of Brüno proved to be much more difficult as it became harder and harder to hoodwink people into being part of his outrageous schemes.

Baron Cohen has plenty of options. Borat won him a Golden Globe award and an Oscar nomination for Best Screenplay, and he has branched out into scripted film work like Talladega Nights and Sweeney Todd.

But whatever he does, it looks increasingly likely that he will have to stop hiding behind his satirical masks and offer over much more of himself -- the real him -- to the studios and the public in order to prosper. And this will surely be his most intriguing performance yet.

- Declan Cashin