Hi, I have a 5yo DS and an 18 month old DD. My five year old has Autism but has never flapped his arms (he does do other repetitive movements such as spinning etc).
My 18 month old daughter seems on track for development but occasionally flaps her arms. It's mainly when she's excited for example when daddy comes home from work or when we pick her brother up from school.
Do other 18 month old toddlers do this?