June and Jennifer were the daughters of Caribbean immigrants Gloria and Aubrey Gibbons. Gloria was a housewife and Aubrey worked as a technician for the Royal Air Force.The twins were born in April, 1963 at a military hospital in Aden, Yemen, where their father had been deployed.  The couple also had 2 other kids, Greta, born in 1957 and David, born in 1959.

The family soon relocated from Barbados—first to England, and in 1974, to Haverfordwest, Wales. They started talking late and when they finally did speak, their words came out garbled. They chirped and squeaked, enunciating the wrong syllables. No one else could understand them. It was like they were speaking a foreign language. They both moved in a sort of synchronicity. 

The family’s children were the only black children in the community. All of the children were often ostracized at school. This proved to be traumatic for the twins, eventually causing their school administrators to dismiss them early each day so that they might avoid bullying. Their language became even more idiosyncratic at this time. Soon it was unintelligible to others. Their language, or idioglossia, qualified as an example of cryptophasia, exemplified by the twins’ simultaneous actions, which often mirrored each other. The twins became increasingly reserved and eventually spoke to no one except each other and their younger sister Rose.

The girls continued to attend school, although they refused to read or write. In 1974, a medic administering vaccinations at the school noted their impassive behaviour and notified a child psychologist. The twins began seeing a succession of therapists who tried unsuccessfully to get them to communicate with others. They were sent to separate boarding schools in an attempt to break their isolation, but the pair became catatonic and entirely withdrawn when parted.

When they were reunited, the two spent several years isolating themselves in their bedroom, engaged in elaborate plays with dolls. They created many plays and stories in a sort of soap opera style, reading some of them aloud on tape as gifts for their sister Rose. Inspired by a pair of gift diaries on Christmas 1979, they began their writing careers. They sent away for a mail order course in creative writing, and each kept an extensive diary and wrote a number of stories, poems and novels. Set primarily in the United States and particularly in Malibu, California, the stories involve young men and women who exhibit strange and often criminal behaviour.

June wrote a novel titled Pepsi-Cola Addict, in which the high-school hero is seduced by a teacher, then sent away to a reformatory where a homosexual guard makes a play for him.The two girls pooled together their unemployment benefits in order to get the novel published by a vanity press.

 Their other attempts to publish novels and stories were unsuccessful. In Jennifer’s The Pugilist, a physician is so eager to save his child’s life that he kills the family dog to obtain its heart for a transplant. The dog’s spirit lives on in the child and ultimately has its revenge against the father. Jennifer also wrote Discomania, the story of a young woman who discovers that the atmosphere of a local disco incites patrons to insane violence. She followed up with The Taxi-Driver’s Son, a radio play called Postman and Postwoman, and several short stories. 

They also kept very extensive diaries.  Often writing multiple times a day. The twins wrote about how trapped or sometimes even possessed or tortured they felt by each other. So even though they only talk to each other, they actually don’t really like each other and they blamed the other twin for the fact that they didn’t talk and was so isolated. 

Here is a quote from one diary: “We have become fatal enemies in each other’s eyes. We feel the irritating deadly rays come out of our bodies, stinging each other’s skin. I say to myself, can I get rid of my own shadow – impossible or not possible? Without my shadow, would I die? Without my shadow, would I gain life, be free or left to die? Without my shadow, which I identify with a face of misery, deception, murder.”

In their later teenage years, the twins began experimenting with drugs and alcohol.  In 1981,so they were 18 ish at the time, the girls committed a number of crimes including vandalism, petty theft and arson, which led to their being admitted to Broadmoor Hospital, a high-security mental health hospital. The twins were sentenced to indefinite detention under the Mental Health Act 1983.

 They remained at Broadmoor for eleven years. June later blamed this lengthy sentence on their selective muteness: “Juvenile delinquents get two years in prison… We got twelve years of hell because we didn’t speak… We lost hope, really. I wrote a letter to the Queen, asking her to get us out. But we were trapped.” Placed on high doses of antipsychotic medications, they found themselves unable to concentrate; Jennifer apparently developed tardive dyskinesia (a neurological disorder resulting in involuntary, repetitive movements). Their medications were apparently adjusted sufficiently to allow them to continue the copious diaries they had begun in 1980  but they lost most of their interest in creative writing.

The case achieved notoriety due to newspaper coverage by journalist Marjorie Wallace of The Sunday Times. Wallace later wrote a book about the two called The Silent Twins, published in 1986.

Marjorie went to visit June and Jennifer in prison, where they were awaiting trial. She thought she might be able to break through their silence.

Wallace says the twins were brought in and that was the most extraordinary moment. First of all, two of the prison warders took one twin in, just leaning like a plank or like a coffin really, on their shoulders and that they just got her in and she sat down and her eyes were downcast. She didn’t move, her hands just hanging by her side. And then the second twin came in and the same thing happened, and they just sat there. And then suddenly I said, do you know, June and Jennifer, I’ve read some of your writings? And suddenly, I saw a little flicker in June’s eyes. She started to look up, and there was a little twitching of her lips, and with great difficulty she got out the words “did you like them?”

So Wallace realizes that the twins desperately wanted to be recognized and famous through their writings, to have them published and to have their story told. And she thought that maybe one way of freeing them would be to unlock them from that silence.

The doctors thought June and Jennifer were deeply disturbed and dangerous. Some days, only one twin would eat, and the next day, the other would indulge as her sister starved. Other times, the nurses would find them frozen in the same pose, even though they were locked in cells on opposite ends of the hospital.

Wallace goes to visit the twins right before they are supposed to be transferred to a new facility. Jennifer told her “ I’m going to have to die, and Wallace sort of laughed and sort of asked what? Don’t be silly. You’re 31 years old. You know, you’re just about to be freed from Broadmoor. Why are you going to have to die? You’re not ill. 

And she said, because we’ve decided. At that point, Wallace says she  got very, very frightened because she could see that they meant it. And then they said, we have made a pact. Jennifer has got to die because they said the day that they left Broadmoor, the day that they were free from the secure hospital, one of them would have to give up their life to really enable the other one to be free. Wallace  later found out that they had been quarreling violently – from the staff at Broadmoor – about who was going to die. And then they passed over a poem that they’d written, which was “that two is your laughing, that two is your smiling and now I’m dead, that too is your crying.”

Jennifer’s cheekbones were very thin and her face looked very flushed. She looked, Wallace says quite afraid. June looked determined. Wallace  was very disturbed at the end of this visit.

Marjorie immediately called their doctors, who said they were monitoring the twins and told her not to worry. She just waited, hoping to get a call that the twins had arrived safely at Caswell. Finally, she heard from one of the doctors.

 In March 1993, the twins were transferred from Broadmoor to the more open Caswell Clinic in Bridgend, Wales. On arrival Jennifer could not be roused. She was taken to the hospital where she died soon after of acute myocarditis, a sudden inflammation of the heart. There was no evidence of drugs or poison in her system, and her death remains a mystery. Some doctors thought the high dose of medication she took at Broadmoor might have weakened her immune system ,but the twins had received the same treatment during their time in Broadmoor. And June was in good health when Jennifer died.

At the inquest, June revealed that Jennifer had been acting strangely for about a day before their release; her speech had been slurring, and she had said that she was dying. On the trip to Caswell, she had slept in June’s lap with her eyes open.  On a visit a few days later, Wallace recounted that June “was in a strange mood”. She said, “I’m free at last, liberated, and at last Jennifer has given up her life for me”. Jennifer was buried in St Martin’s Cemetery in Pembrokeshire, Wales.

After Jennifer’s death, June gave interviews with Harper’s Bazaar and The Guardian.  By 2008, she was living quietly and independently, near her parents in West Wales.  She was no longer monitored by psychiatric services, has been accepted by her community, and sought to put the past behind her. A 2016 interview with her sister Greta revealed that the family had been deeply troubled by the girls’ incarceration. She blamed Broadmoor for ruining their lives and for neglecting Jennifer’s health. She had wanted to file a lawsuit against Broadmoor, but Aubrey and Gloria refused, saying it would not bring Jennifer back.

The pair were the subject of the 1986 tv drama The Silent Twins, broadcast on BBC2, and an Inside Story documentary Silent Twin – Without My Shadow, which aired on BBC1 in September 1994. A play based on Wallace’s book, titled Speechless, debuted in London in 2011.