As part of "Nightline Prime: Beyond Belief" series, we take a look at twin-tuition, the unspoken, telepathic communication between twins. The number of twins born today has doubled since a generation ago -- from three to six million sets of twins a year. Fraternal twins, like siblings, share 50 percent of their DNA, but identical twins share 100 percent of their DNA. A survey of 5,500 twins found that 1 in 5 identical twins said they have experiences some form of telepathy between each other. J.J. Pearce High School in Richardson, Texas, set the Guiness world record for the most sets of multiples in a single grade: 10 pairs of twins and a set of triplets. Tune into "Nightline Prime: Beyond Belief" Wednesday, June 29 at 10 p.m. ET/PT.
Amy Gutierrez/ABC News
"Twin-tuition" can happen mentally or psychically, and such was the case with identical 7-year-old twin sisters Ally and Kayli from Seven Falls, Pa. The sisters were playing at a mall playground when Kayli got hit in the face and developed a black eye. Ally, who was playing on another side of the playground and was uninjured, started to show signs of bruising in the exact same place.
Identical twin sisters Terry and Linda Jamison coined the phrase "twin-tuition." The women still dress alike, finish each other's sentences, and claim to have been telepathic in the womb. But they don't just read each other's minds, the Jamison sisters claim they are telepathic and can see the future. "It's as if we're operating on the same frequency or vibration, almost as one organism." Linda said.
Courtesy Linda and Terry Jamison
When twin brothers Christopher and Andrew Watson of Lutterworth, Leicestershire, England, were in a car wreck at age 16, Andrew walked away from the accident, but Christopher sustained extensive brain damage and slipped into a coma. Doctors say when Andrew walked into his brother's hospital room, Christopher's blood pressure would go down and his heart rate would settle. "How he knew Andrew was there I don't know," their mother Helen Watson said. "The staff noticed that straight away his vital signs normalized."
Courtesy Helen Watson
They are arguably the best tennis doubles team to ever walk on the court. Identical twins Bob and Mike Bryan have won 10 Grand Slam titles from Wimbledon to the French Open. Watching them play shows how incredibly similar their movements are. "We're kind of blown away, like 'Geeze, we're bouncing at the same time and we're stopping at the same time. This is weird," Bob Bryan said.
Twin-Tuition: Meet the Twins
Psychology professor Dr. Nancy Segal explained that since identical twins have the same DNA, their brains process information identically. Ana Delia Monte de Oca Sosa and Begonia Garcia Alfonso, twins born on the Canary Islands off the coast of Spain, were switched at birth and were raised by different families just 23 miles apart. Both said that for years they mistaken for one another. The sisters thought it was just a coincidence until 36 years later when they met face-to-face. Shown here is Delia as an infant.
Courtesy Ana Delia Monte de Oca Sosa
Swedish psychologist Adrian Parker attempted to study the psychic connection between twins at the Twin Studies Center in St. Thomas Hospital in London. Parker conducted psychological experiments using four sets of twins who believed they had experienced distinct and frequent telepathic events. By placing each twin in different rooms, Park applied a series of measured stimuli to see how each would react. The results were surprising. Tune into "Nightline Prime: Beyond Belief" Wednesday, June 29 at 10/9c.