Autism is mainly caused by a child ’ s genes , a major study of British twins has found . Scientists said that , in the average boy or girl with autism , genetics explain up to 98 per cent of the illness . The research , by King ’ s College London , found the condition is highly inheritable . Controversial research linking autism with the MMR jab has been widely discredited , but more recent concern has focused on the condition being fuelled by environmental factors such as pollution . The team compared the behaviour of pairs of identical twins , who share all their DNA , and non-identical twins , who have only half their genes in common ( file picture ) With cases of autism much more common today than in the past , many fear it is also being caused by modern lifestyles . Estimates suggest that as many as one in 100 people in the UK now has autism . But the researchers said their study suggested that lifestyle and environmental factors were a distant second to genetics . The team compared the behaviour of pairs of identical twins , who share all their DNA , and non-identical twins , who have only half their genes in common . They found the condition was far more common in identical twins than in non-identical ones . The study , in the journal JAMA Psychiatry , concluded that rogue DNA explains between 74 and 98 per cent of the cause of the average case of autism . If genes are key , the recent rise in cases could be explained by more people being correctly diagnosed with the condition . Controversial research which linked autism with the MMR jab has now been widely discredited ( file picture ) Dr Francesca Happe told the BBC : ‘ Our findings suggest environmental factors are smaller , which is important because some parents are concerned whether things like high pollution might be causing autism . The main consensus now is that the rise in diagnosis has more to do with increased awareness of the condition. ’ Dr Judith Brown , of the National Autistic Society , said : ‘ Autism is a highly complex story of genes not only interacting with other genes , but with non-genetic factors too . ‘ This large population-based twin sample is significant because it helps us to understand much more about the role genetics play in autism and opens up the possibility of whole families gaining a better understanding of a condition they may share. ’ But she added : ‘ We are still a long way from knowing what leads to autism . ‘ What people with the condition , their families and carers need most of all is access now to the right kind of support to be able to lead full lives. ’ The study looked at 128 pairs of twins in which at least one sibling had an autism diagnosis , between the ages of 12 and 14 . Lead researcher Beata Tick said : ‘ This study shows that the genes are very important and the increased rate of autism is more down to awareness than environmental factors. ’ Latest figures suggest more than one in 100 people in Britain has autism , including related conditions such as Asperger ’ s syndrome . This is a ten-fold increase on 30 years ago . Symptoms vary , but usually revolve around difficulty with social interaction , communication problems and a need for a strict routine . Many patients are treated with speech and behavioural therapy . Although drugs can be prescribed to control symptoms such as aggression or hyperactivity , there is no cure .
Controversial research has linked autism with MMR jab and environment . Score: 7