Throughout chronicle , twin studieshave grant some unbelievable scientific insights – NASA even sent one of a pair of identical twins tospace . The opportunity to consider thisunique groupis too good to pass up , and now a new analysis of twin data has drawn a fascinating connection between autism and the mysterious phenomenon of synesthesia .

Many the great unwashed will have heard of synesthesia in the context of use of people who can“see ” medicine , but in realness the unlike sensory effects of the condition can go far beyond that . Some people can“taste ” speech ; others“see ” meter , or in the display case of one blind person,“feel ” metre as a texture . And , in the far less fun example ofmirror - touching synesthesia , a small percentage of multitude can literally feel the corporeal sensations being experienced by those around them – including pain .

In all vitrine , synesthesia follow down to a cross of the wires between unlike sensory processes in the brain . In seek to learn why this pass off , scientists have antecedently observe that autistic people are alsomore likelyto have synesthesia , but that still left them no closer to reason just what this link might be .

Something else that ’s been noticed about synesthesia is that it tends to run in families . Speculating that there could therefore be some genetical inheritance at study , a team of scientists turned to data from the Child and Adolescent Twin Study in Sweden ( CATSS ) , which included twins born between 1999 and 2003 .

The final sample admit 2,131 pair of Gemini , of which 658 wereidentical , 765 were non - identical but of the same sex , and 708 were non - indistinguishable and of different sexes . participant were screen for eight of the more common types of synesthesia , including types where letter or numbers trigger the percept of a people of colour , and also took part in anassessmentfor autistic trait .

The results showed that self - report synesthesia was powerfully yoke to a category of trait frequently learn inautisticpeople , known as the RRBI - viosterol domain , which stand for “ insistent demeanour , restricted stake and attention to detail . ” These canincludethings like an intense , extremely - focused interest in a theme , attachment to particular aim , or performing repetitive move such as hand - flapping ( often lie with as ego - stimulating behavior or , more colloquially , “ stimming ” ) .

“ The tie between individual differences in synesthesia and autistic trait was estimated to be preponderantly under genetic influence and seemed to be mainly push back by non - social autistic trait ( repetitive behaviours , bound sake and attention to detail ) , ” the generator wrote in their paper .

As such , they concluded that “ the data link between synaesthesia and autism might domiciliate in shared genetic causes , related to non - social autistic trait such as alterations in percept . ”

Whilst thegeneticconnection appears to play the strongest function , according to the bailiwick results , environmental factor that differed between each fellow member of a readiness of twins were also implicated . The authors observe that this is in line with previous research , which has shown environment to be a particular component in the maturation of types of synesthesia in which numbers and alphabetic character are perceived as having colors .

There are some limitation to the research , such as the fact that not all potential types of synesthesia could be included and the fact that the synesthesia data relied on ego - coverage , which is always open to bias . But the subject squad is optimistic that more work will be , to make on the evidence they ’ve amass and hopefully improve our agreement of bothautismand synesthesia :

“ We hope that our findings will inspire future research on environmental factor influencing synaesthesia , the shared inherited mechanism of autism and synaesthesia , and the specific behavioural lineament partake in between the two phenomena , informing their share and non - divided etiology . ”

The study is published inProceedings of the Royal Society B : Biological Sciences .