At the time of Charles and Diana’s wedding in 1981, Susanna Crossman was nearly nine. “We are against it,” she recalls, “but we watched it anyway… It was beautiful, but I know marriage is a patriarchal institution, a capitalist trap, a snare. You can read about it in Spare Rib, or if you ask community members, someone will tell you marriage is legalised rape.”

For 15 years from the age of six, Crossman lived with her mother, brother and sister on what would generally be called a commune – though members insisted on the word “community”. Fifty people shared a 60-room house on a 31-acre estate in the English countryside, but they were very clearly divided, she writes, into “two distinct social groups”: the Adults and the 18 Kids, between two and 10 years old.

She is keen to capture “the glorious buzz of revolution, alongside the isolation, the trauma, the shame” of her life there. She has memories of “bacchanalian ecstasy” and still values the “feral autonomy, self-reliance, open-mindedness and creativity” that characterised her childhood. But although her own feelings remain fiercely ambivalent, it is hard not to feel outraged by what it meant for her to be “a prop in the Adults’ utopian dream”.

Since making sure the boiler worked properly was considered “symbolic of the patriarchy”, the Kids were permanently cold, and Crossman reports “terrible coughs”. She experiences “a certain feeling of horror” when realising “how dirty I was as a child”. Her mother refuses to let her take up a place at a grammar school on the grounds that “we don’t believe in the selective process or class inequality”, but her attempts to fit in at a local comprehensive were hampered, she tells us, not only by a lack of hairspray and frosted lipstick but “a zillion other things that I do not have, like hot water and an iron”.

More significant, Crossman claims that their hostility towards the traditional family led the Adults in the community to “believe that parental affection was a trap, and indifference guaranteed freedom”. When a girl complains that another girl has hit her, a man “replies, using the words the Adults always say: ‘Deal with it yourself. Sort it out, Tina.’ In the community, autonomy is better than dependency. It is not good to ask for help, even if you are five.” Since no one had ever explained the dangers of electricity, Crossman nearly electrocutes herself. She also remembers how twin girls had to be removed from the community after they “found a razor in the communal bathroom. They tried to shave their little faces, and cut their skin into ribbons of red.”

Her mother very much lived by this philosophy of non-intervention. She refuses to offer any guidance when a teacher makes a patronising comment and Crossman decides she wants to leave school. And she seems oblivious to the dangers of sexual abuse when a man in the community proposes a private massage to her young daughter.

Even as a child, Crossman rebelled against some of the strict rules of communal life that underlay the talk of freedom. All sweets had to be shared in the school van, but, she tells us, this only spurred her to “keep a flavourless boulder of bubble gum glued under my bed. For weeks, I mash on a grey, sticky ball coated in fluff. But I do not care. The gum is mine.”

Such vivid and poignant details make Home Is Where We Start a powerful memoir of a particularly unusual childhood, though its later sections aren’t so successful. Crossman describes how she has tried to forge an authentic personal identity from the collective self once imposed on her but little of the material about teenage indiscretions or her life in France with her partner and daughters has the freshness and immediacy of the scenes from life in the community. She also offers some more general reflections on the nature of home, childhood and communal living. Unfortunately, she has a weakness for overextended metaphors and a strange obsession with etymology. (Even when describing how she ran along a corridor on the way to what turns out to be a horribly abusive encounter, she stops to give us the derivation of the word “corridor”.)

Most unsatisfactory of all is the pointless “poetic” speculation. When Crossman was only three months old, a man in a tractor knocked over a wall and killed her sister Rachel. She plausibly suggests that this tragic accident has haunted the family ever since but also feels the need to describe the scene: “A jewelled jade lustre sways in the breeze…Perhaps [the farmer] hums Donny Osmond’s Puppy Love, for it is a summer hit that year.” And perhaps, more likely, not. Much of this book is concrete, disturbing and moving. It is a real pity that Crossman’s editor didn’t encourage her to rein in her excesses.

• Home Is Where We Start: Growing Up in the Fallout of the Utopian Dream by Susanna Crossman is published by Penguin/Fig Tree (£18.99). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply