Scientists have uncovered medical clues to why some people with autism do not like hugs.
The fragile X syndrome, caused by a mutant gene in the X chromosome, has been linked with why many autistic people do not like close contact.
It is now thought that the mutation causes crucial delays in the development of the brain in the womb.
The part of the brain which is wired to respond to touch is thought to develop much later in the brains of people on the autistic spectrum.
Dr Gina Gomez de la Cuesta, from the National Autistic Society, told the BBC: "Autism is common in people with fragile X syndrome, however there are many other causes of autism, most of which are not yet fully understood."
She added: "Understanding how the brain works when a person has fragile X syndrome could help put some of the pieces together about what is happening in the brain when a person has autism, but it is not the whole story."
Independent advice on private healthcare