Children who have an aunt or uncle with autism are more than twice as likely to be diagnosed with the developmental disorder too.

New research finds that about 3 to 5 percent of kids whose parents have a sibling on the spectrum also have autism themselves. By comparison, the condition is seen in about 1.5 percent of all children in the general population.

Researchers examined health records for nearly 850,000 children born in Sweden between 2003 and 2012 and their families. About 13,000 of the kids were ultimately diagnosed with autism.

Among children whose mothers had a sibling with autism, the condition was three times more likely than for those in the general population, according to findings published recently in the journal Biological Psychiatry. If the child’s father had a sibling on the spectrum, then they had double the risk of the general population.

The study found that the odds were not meaningfully different if the parent had a brother versus a sister with autism.

The findings provide the first population-wide estimate of autism risk for children with aunts or uncles on the spectrum, according to the National Institutes of Health, which funded the research.

“The results offer important new information for counseling people who have a sibling with ASD,” said Alice Kau of the Intellectual and Developmental Disabilities Branch of NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development.

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