“P'ut takana!” one girl says insistently, and her twin sister immediately reaches for the cookie jar. To anyone else it sounds like nonsense. To the sister, it means: “Get the jar.” This is what cryptophasia looks like — and it is where one of the strangest stories in linguistics begins.
Cryptophasia (from the Greek kryptos — secret, and phasis — speech) is an autonomous communication system that twins create spontaneously. It is neither baby talk nor a pathology — something between a language and a game: words from the native tongue deformed beyond recognition, their own grammatical rules, and gestures that replace half of every phrase.
According to several linguistic studies, up to 48 percent of identical twins and around 40 percent of fraternal twins go through a phase of cryptophasia. It most often emerges between the ages of two and four and fades on its own by school age. In 96 percent of cases, without any lasting effect on speech development. But there are exceptions that have changed the way scientists think about language itself.
Linguists who have studied cryptophasia across different twin pairs identify several stable mechanisms that appear independently — even in children from different countries and language families.
Twins do not invent words from scratch — they deform already-heard ones according to their own rules: swallowing syllables, swapping sounds, attaching new suffixes. The result is a word that sounds like random noise to any outsider, but carries a precise meaning for the second twin.
Real languages are full of redundancy: pronouns, agreement, articles. Cryptophasia works on the principle of “only what is necessary”: no pronouns (only names), no conjugations, word order fixed by importance — the most important thing always first. This closely resembles the structure of early pidgin languages that arise when two linguistic communities come into contact.
Twins develop in a mode of constant mutual correction: one drops a syllable, the other copies it, the error becomes fixed. They are literally building grammar together, in real time. This is why their system cannot be reproduced without the partner — the rules exist only within the pair.
Linguist Peter Bakker called cryptophasia a “time machine”: it shows what language looked like before it became language.
In the late 1960s, twin girls were born into an American family called Kennedy. They had seizures as infants, and their parents concluded they were intellectually disabled. The girls were isolated from other children and left in the care of their deaf-mute grandmother, who spoke only German. They grew up without normal language contact with the outside world — and built their own.
When journalist Ron Jenkins overheard their conversation in 1977 and wrote about it, linguists were astonished. The girls called themselves Poto and Cabengo. Their language turned out to be a complex blend of English and German with unique neologisms: “pinit” for finish, “nigh” for good night, “Liba Cabingoat, it!” — meaning “Dear Cabengo, eat!”
Speech therapists at a San Diego children’s hospital tested the girls. Result: both had IQs within the normal range. The speech delay had been caused not by neurology but by emotional deprivation — their parents, believing them hopeless, had barely spoken to them. The diagnosis was withdrawn. The girls were taught English — years late, but successfully.
In 1979, French director Jean-Pierre Gorin made a documentary called “Poto and Cabengo.” It became a landmark case study in how the social environment shapes — or destroys — speech development.
June and Jennifer Gibbons were born in 1963 in Haverfordwest, Wales, to a Barbadian immigrant family. From their first days at school they faced relentless bullying — as “black outsiders” with incomprehensible speech: their English came out as a high-speed warble because they swallowed so many syllables.
Their response was total withdrawal. The sisters stopped speaking to anyone but each other. At fourteen, an attempt to separate them and send them to different boarding schools sent both into catatonic stupor — unresponsive to everything around them. They were urgently reunited.
By nineteen they were living in complete isolation, communicating at a rate of around 300 words per minute in a language no one outside their pair could decode. In desperation they began committing petty crimes — arson, shoplifting. In 1981 a court sent them to Broadmoor Hospital — a high-security psychiatric institution for dangerous offenders — where they spent eleven years.
In 1993, during a transfer to a different facility, Jennifer suddenly died of acute myocarditis. Toxicology found nothing. June immediately began speaking ordinary English — for the first time in decades. She later explained to journalist Marjorie Wallace, who had spent years with the sisters and written a book about them: “We had an agreement. One dies, the other starts to live.”
Doctors linked their case to autism and catatonia. But June herself named the real cause differently: “No one heard us. We only heard each other.”
The Gibbons case is an extreme and tragic one. But it defines with precision the danger of cryptophasia — not in itself, but in combination with isolation: a language that becomes the only channel of connection with the world turns into a barrier rather than a bridge.
Not every story ends in tragedy. Brothers Thomas and Christopher Youlden from the United Kingdom started with ordinary childhood cryptophasia — and never stopped. By the age of thirty their language “Umeri” had its own grammar of two hundred rules, a vocabulary of several thousand words, and a writing system. It was their twenty-sixth jointly created language.
“Umeri is not an artificial language,” the brothers said. “It is a living organism. It exists only for the two of us and will die with us.” Both worked as linguists and used their personal experience in academic research on language construction.
The Youlden case shows the other side of the same coin: with normal socialisation and a maintained connection to the outside world, cryptophasia can become a tool for creativity rather than isolation.
Two facts that often surprise even people who think they know everything about twins.
Around 25 percent of identical twins are mirror images of each other: one right-handed, the other left-handed, birthmarks placed symmetrically (one on the left cheek, the other on the right), hair whorls spiralling in opposite directions. This occurs because of late splitting of the fertilised egg — on days 9 to 12, when the left-right axis is already beginning to form. Mirror twins develop cryptophasia more frequently — possibly because their brains literally mirror each other’s speech patterns.
Every eighth pregnancy begins as a multiple. But by around week 12, one embryo “disappears” — its DNA absorbed by the surviving twin or the placenta. Around 40 percent of these children show microchimerism: cells carrying the DNA of the “absorbed” twin persist in their body. This may affect immune response and, according to some data, subtle behavioural characteristics — though the mechanisms here remain largely hypothetical.
Cryptophasia is neither a pathology nor telepathy. It is a normal stage of speech development in twins that resolves on its own in most cases. But three famous cases — Poto and Cabengo, the Gibbons sisters, the Youlden brothers — show that the environment in which the language exists determines everything: it can become a creative laboratory or a closed system with no exit.
What the Gibbons sisters lacked and what Poto and Cabengo were eventually given was not the right genes or ideal neurology. It was the attention of an adult who heard the child and responded in a language both could understand.
Any language — secret or shared — exists only because there is someone listening.
If you are planning a multiple pregnancy or expecting twins, Module 3 (Biohacking & Preconception) and the Partners section can help you find specialists in neonatology and speech development.
an autonomous communication system spontaneously created by twins from deformed elements of their native language. Not a pathology; in most cases disappears by ages 3–4.
the presence of cells carrying genetically distinct DNA in a person’s body. In children who “absorbed” a twin embryo in the womb, cells with its DNA may persist in their tissues.
identical twins showing physical mirroring: opposite handedness, symmetrically placed birthmarks, opposing hair whorls. Occurs when the fertilised egg splits late, on days 9–12.
the absence of emotional responsiveness from significant adults in early childhood. One of the best-documented factors in delayed speech development.