Several small studies conducted over the last three decades have found that it is much more common for identical twins to be diagnosed with autism than it is for fraternal twins.
Why is autism more common in twins?
Studies in twins have shown that autism has genetic origins: A child is more likely to have autism if his or her sibling or twin also has the disorder. But there is also evidence that factors other than genetics, collectively referred to as ‘the environment,’ play a role.
Can one twin be autistic and the other one not?
Identical twins share nearly all of their genetic information, so it would be expected that both twins would fall on the autism spectrum if there were a genetic cause. Research has shown that when one identical twin is on the autism spectrum, the other twin also falls on the autism spectrum in 60-90% of the cases.
Who is at high risk for autism?
Children born to older parents are at a higher risk for having autism. Parents who have a child with ASD have a 2 to 18 percent chance of having a second child who is also affected. Studies have shown that among identical twins, if one child has autism, the other will be affected about 36 to 95 percent of the time.
Are twins more likely to have mental illness?
The strongest risk factor for suicide is mental illness and studies show that mental illness is slightly more common among twins.
What percentage of twins are autistic?
Based on data from 192 pairs of twins, the new study found a concordance rate for autism spectrum disorders of 77 percent among identical twin boys and 31 percent among fraternal twin boys.
Are both twins usually autistic?
Studies in identical twins have shown that autism has a strong genetic basis: If one identical twin has autism, the other one has it, too, as much as 90 percent of the time. The new work supports these estimates: In 64 of the 78 twin pairs, both twins have an autism diagnosis.
What environmental factors can cause autism?
What Environmental Factors May Be Associated With Autism?
- Advanced parental age at time of conception.
- Prenatal exposure to air pollution or certain pesticides.
- Maternal obesity, diabetes, or immune system disorders.
- Extreme prematurity or very low birth weight.
Does autism run in families?
ASD has a tendency to run in families, but the inheritance pattern is usually unknown. People with gene changes associated with ASD generally inherit an increased risk of developing the condition, rather than the condition itself.