Sam Taylor-Wood's film, Nowhere Boy, paints John Lennon's formative years in the broadest of brush strokes. He is a troubled but gifted teenager caught between two women, two worlds. His mother, Julia, is working-class, wild-spirited and mostly absent, and his aunt, Mimi Smith, is respectable, strict and domineeringly present. Julia loved Lonnie Donegan; Mimi listened to Tchaikovsky. In Lennon's case, nature triumphed over nurture.

Lennon was born during an air raid on 9 October 1940. His father, Alfred "Freddie" Lennon, was a merchant seaman and only fitfully present during his son's childhood. When he returned to Julia in 1944 after a long absence, she was pregnant by another man. It was Mimi who complained to the social services that her sister was unfit to look after the young boy, an intervention that began the sisters' long battle for John's affections. One of the more traumatic childhood scenes, shown in flashback in Nowhere Boy, shows the five-year-old John being instructed by Freddie to choose whether he wanted to live with Julia or him. John first chooses Freddie, then, in tears, runs up the street after his mother. After that, Freddie disappeared from Lennon's life for two decades, only to resurface after his son had become famous. By then, Mimi was Lennon's mother in all but name. When an American magazine offered to publish her memoirs, Mimi rang and asked for his advice. "Take the money, Mimi," he said, "and tell them I was a juvenile delinquent who used to knock down old ladies." There was more than a grain of truth in that description.

The John Lennon that Aaron Johnson portrays in Nowhere Boy, though, has had his sensitivity amplified and his arrogance turned down. He dresses like a teddy boy, but there is barely a glimpse of the semi-delinquent behaviour of his grammar school years – the gangs he led, the shoplifting, the hapless pupils and teachers he bullied – or his fascination with, the disabled and the disfigured. In A Hard Day's Night, someone asks Ringo if he is a mod or a rocker. "I'm a mocker", he retorts. But he wasn't. Lennon was.

Lennon filled notebooks at Quarry Bank school with drawings of human grotesques and, as his first biographer, Ray Coleman, put it, "developed an instinctive ability to mock the weak, with whom he had no patience". An early girlfriend, Thelma Pickles, who hung out with Lennon at art school, later recalled: "Anyone limping or crippled or hunchbacked, or deformed in any way, John laughed and ran up to them to make horrible faces."

The cruelty, like the anger that occasionally erupted from time to time into physical violence may have had its roots in his constant childhood feeling of not quite belonging anywhere, or to anyone. Mimi treated him sometimes as her son, sometimes as an equal. Julia, doted on him when she saw him, but was absent for most of his childhood.

The death of the young Lennon's surrogate father, Mimi's husband George, in 1955, was the first of four deaths that would wound and harden him. Julia died when John was 17; his best friend, Stuart Sutcliffe, died suddenly from a brain haemorrhage in 1962; and his manager and mentor, Brian Epstein, who nursed an unrequited love for Lennon, died of an overdose in 1967.

Julia's death was the most unexpected. She was hit by a speeding car driven by a policeman; Lennon retreated into himself, bonding with the young Paul McCartney, who had also lost his mother as a boy, but barely talked about the loss of Julia until years later when his long bout of primal therapy helped create the musical cry for help that is "Mother" on his first solo album.

Lennon's most recent biographer, Philip Norman, has suggested that the 14-year-old Lennon was sexually attracted to his mother, having become aroused when he accidentally touched her breast. "I was wondering if I should do anything else," Lennon told a journalist years later, "I always think I should have done it. Presumably she would have allowed it." Taylor-Wood's film hints at, but pulls back from, that transgressive moment, which is probably for the best given Lennon's tendency to say things for effect. His adolescent need to rebel and offend stayed with him long into adulthood, his maturity arrested by the gilded prison of celebrity and the copious amounts of LSD he took in the mid to late 60s when he seemed intent on obliterating his troubled psyche.

Such was the emotional tumult of John Lennon's early years, it is difficult to imagine him having an uneventful life even if he hadn't been famous. The restlessness that willed him into stardom was such that it helped overthrow the last vestiges of Victorian Britain in the youth-led surge that shaped the 60s.

His upbringing was comfortable in a material way but unstable emotionally, and in the art school years that end the film, he found a milieu where he almost belonged. He was a bohemian and a rebel, by turns arrogant and insecure; the classic outsider who came to define the boundaries of the mainstream by reacting against them; the nowhere boy who became Britain's most famous pop star but never quite transcended his troubled childhood.

• This article was amended on 7 January 2010 because we incorrectly said that it was John Lennon in A Hard Day's Night who referred to himself as a "mocker" but it was Ringo who said it.

