According to researchers, twins have a greater risk of developing autism. Two studies, one in the United States and one in the United Kingdom, suggest that environmental factors may play a role. Prior studies showed that genetics play an important part in autism development, but the two recent studies say experiences in the womb are also involved.
A spokesperson for the National Autistic Society said the results of the studies add to prior findings suggesting exposures in the womb contribute to autism development. The spokesperson added, however, that researchers have not found any specific prenatal exposures as contributory.
The Two Autism Studies and Environmental Factors
In one study, a Columbia University geneticist looked at families in which at least two siblings had autism. The researcher found that a significant number of identical and fraternal twins had autism. His research found, more specifically:
- Of the 166 sibling pairs identified with autism, 17 were identical twins and 12 were fraternal twins
- Identical twins are 12 times more likely to develop autism than the general population
- Fraternal twins are four times more likely to develop autism than the general population
The second study at St. George’s Hospital Medical School in London identified 79 sibling pairs with autism. The findings showed that identical twins are 14 more times likely to develop autism. Figures for fraternal twins were not available.
The researchers in the studies say that the battle in the womb between twins for food may be a factor in autism. The fiercer battle between identical twins may explain the higher incidences of autism when compared to fraternal twins. Identical twins are closer in the womb because they lack the membranes that separate fraternal twins.
As a whole, the studies suggest that there is more to autism development than just genetics. Despite the studies’ findings, the National Autistic Society warns that doctors need more research to reach a conclusion about twins and environmental factors. Currently, specific medical conditions contribute to only 10 percent of autism cases.
If you or someone you know has fraternal twins afflicted with autism, a birth defect lawyer can explain any legal recovery that may be available. Contact an experienced birth trauma lawyer for a free initial consultation about what legal options are available to you.
