The development of young siblings of children with autism from 4 to 54 months.

Gamliel et al. (2007) watched baby brothers and sisters of autistic children every few months from age 4 to 54 months. They gave the same thinking and language games to both the high-risk siblings and to kids with no family history of autism.

The team used simple tests like looking at pictures, copying block towers, and naming objects. They wanted to see if the siblings kept up, fell behind, or caught up over time.

Most siblings started a little lower on thinking and talking tasks. By 4½ years the thinking gap had closed, but small language differences stuck around for some kids.

In plain words: the brothers and sisters got plenty smart, yet a few still mixed up words or needed extra time to answer questions.

Brignell et al. (2024) kept following the same crew until age 11. They show the language gaps keep shrinking, so the small lags seen at 54 months are not a life sentence.

Cox et al. (2015) asked moms to jot down worries in a diary. Mothers spotted language and social concerns as early as 6 months, lining up with the delays Ifat later measured.

McGarty et al. (2018) add that the slowest-growing babies in gesture and understanding usually turn out to have ASD themselves. This helps you know which siblings need the closest watch.

You can reassure families that most siblings will catch up in thinking skills by preschool. Still, keep testing language every six months; small gaps can linger and are worth targeting early. Use parent diaries and simple gesture checks to flag the few who may need a full autism evaluation.