Josh Howie is sitting crosslegged in the middle of a Soho street, looking uncomfortable. The Knowledge photographer thinks the pose will look great but the stand-up comedian isn’t convinced, no doubt swayed by the Japanese tourists who have stopped to giggle and take his picture. “Still,” he says, peering up sheepishly through his NHS specs at the bustle surrounding him. “It does represent what’s going on inside my head.”

Howie’s turbulent life – chunks of which find their way into his neurotic new Edinburgh show – is a psychoanalyst’s dream. His mother is Lynne Franks, the PR guru whose chaotic New Age existence helped inspire her friend and client Jennifer Saunders to write Absolutely Fabulous with its scatty matriarch Edina Monsoon.

He had been a devotee of Buddhism and Native American spirituality before he was old enough to drive. He then ran off to Israel, trained to become a rabbi and got thrown out after being caught in flagrante with a gentile girl, before finally opting for the relaxing world of stand-up.

Having repaired to a nearby restaurant after his photographic ordeal, Howie is engaging company, although he admits to a bundle of hang-ups: “We’re talking now and part of me is thinking, ‘How’s this being interpreted?’ My brain never shuts up, I’m always second-guessing, third-guessing.”

Talking about his high-profile mum, who appeared on I’m a Celebrity . . . Get Me Out of Here last year, is particularly awkward. “Not through embarrassment – it’s just a bit twatty. I’ve had friends who didn’t realise for years and in the comedy world I’ve kept it very quiet [he uses his father’s name]. In a way it’s why I got into comedy, because there is no such thing as nepotism. It’s pure survival of the fittest.”

Until his mid teens, Howie’s family were all practising Buddhists; his parents were local chapter leaders and “100 Buddhists came to our house every week and chanted together”. They later undertook a Native American-style “vision quest”, in which each of them was dropped alone in the wilderness for 24 hours to await the arrival of their spirit creature. The 15-year-old Howie went back to Mill Hill, his North London boarding school, and told his classmates, “I’m now Blackhawk, I can regress people to their past lives and dissolve clouds with my mind.”

It’s not hard to see why Saunders thought the Howies were comedy gold. Ab Fab was conceived when the two families were on holiday together, and had Franks’s blessing, although Howie would rather not talk about her subsequent emotional reaction to it.

“But my sister and I thought it was very funny,” he insists. “And surreal: the bin was the same as ours, the kitchen was the same as ours, the grandma was like our grandma.” He also admits to a sliver of identification with Saffie, Edina’s sceptical daughter: “I’d open the door and there’d be 20 hippies with bongo drums and I’d slam the door in their faces.”

When his parents divorced, Howie took refuge in the Judaism that his feminist mother had rejected as patriarchal. “I was vaguely aware from hearing my parents argue that my mum was ‘a f***ing Jew’.” But it was only when he was 16, and watching Exodus, the Paul Newman film about the flight of the Israelites, that he brought up the subject with his delighted grandmother, with whom he and his wife live.

Fuelled with Zionist zeal, he went to Israel to work on a kibbutz and then begin training as a rabbi. “I would call up my mum, reserve charges, saying, ‘Hey, God wrote the Torah and created the world in six days,’ and she would say that I was being brainwashed, but be really hypocritical about it: ‘My guru says you are being brainwashed’. ”

After his sexual indiscretion in Israel, he returned to London, retaining a more liberal version of his religious views and taking new inspiration from American Jewish comics. It was Lenny, the Dustin Hoffman film about Lenny Bruce, that convinced him to try stand-up, while his squirm-inducing routines, which touch on everything from the Holocaust to incest to racism, owe much to Larry David. And the neuroses, glasses and interest in films (he has directed several shorts and presents an indie cinema show on Sky TV) betray another iconic influence: “I used to say, give me ten years and I’ll be the Jewish Woody Allen.”

Howie mantains that his current religion has more comedic potential than his former one: “People don’t have the same reference points with Buddhism, whereas with Judaism people have certain preconceptions that I can mess with.”

Touching as it does on so many real experience, the new show, he concedes, will be “very uncomfortable” viewing for his family. “Almost to the point of saying to them ‘Don’t come.’ ” He pauses. “But it’s my life, and I’ve got to talk about these things.”

Josh Howie, Pleasance Courtyard, Edinburgh, Jul 30-Aug 24 (www.joshhowie.com 0131-226 0000)