It’s like something out of a horror movie: siblings with a creepy ability to know what the other is thinking. The theory, promulgated by pop culture, reinforced by urban legends, and confirmed by parental paranoia, is that closeness between siblings is strong enough to produce telepathic episodes, particularly in moments of great emotion or significance. These eerie myths even more commonly surround twins and multiples, perhaps due to their rare and unique bond.
When one twin falls down on the playground, the other — miles away at home — starts crying with seemingly no impetus. Or siblings separately pick out the exact same outfit to wear with no apparent influence between the two. Instances of sibling telepathy like these are widely reported in our culture, but according to scientists, there’s little hard evidence behind the stories. Still, if your tots do have something supernatural going on, there’s an upside: you’re sure to get some lucrative offers from reality TV producers.
A 2008 study published in the Journal of Cognitive Neuroscience employed MRI testing to examine brain activity for conclusive proof of so-called parapsychological phenomena, or psi. The researchers argued that, if any form of telepathy exists, it would show up in brain scans as neurological activity. The study set out to involve subjects, including siblings and identical twin pairs, with biological and emotional connections conducive to telepathy. Arranged in these pairs, one person attempted to transmit a mental picture from a different room, while the scientists observed brain-image data from the receiving partner. They collected data on more than 3,600 guesses, as the receivers used buttons to indicate when they thought the image matched the one sent telepathically. Whether the guesses were right or wrong — facts known only to the researchers, not the subjects — the brain scans were impossible to tell apart. The lead researchers concluded that the study offered some of the most compelling evidence that telepathy and other forms of supposed psychic phenomena simply do not exist.
Not unlike the creepy twins from “The Shining,” toddler siblings sometimes exhibit remarkable behavior that can seem beyond the ordinary. It’s actually no secret that many twins develop their own private, shared language as toddlers. In the vast majority of cases, such cryptophasia, or twin language — also sometimes shared by non-twin siblings — is merely a stepping stone of expressive babbling on the way to full language development. In rare cases, siblings may actually develop a type of simple language with linguistic structure, notes a 2011 Slate.com report exploring the phenomenon of cryptophasia. Siblings can also have a deep connection that extends to nonverbal behavior, so messages are shared through body language without either child having to speak a word. Some might call this talent ESP, but it’s most likely simple intuition. In this way, toddlers’ communication can appear to border on clairvoyance, when it’s really confirmation bias — our tendency to notice behaviors that will confirm what we already believe — at work.
Research reviewed in the the Journal of Psychotherapy Practice and Research noted that the perplexing coincidences that twins and multiples experience have much more to do with their genetic relationship than to any paranormal powers. Even twins raised apart show remarkable similarities in their development, so synchronous behaviors and feelings in toddler twins may stem from their similar genetic profiles. Among siblings, imitation is also the sincerest form of flattery, so keep in mind that what appears to be mind-reading could actually be highly evolved modeling — particularly in a relationship between a younger child and an admired older sibling.