5. Prefers to be alone
It can take a while for children to begin developing the ability to relate to and communicate with others. However, by their first birthday, most children start to show interest in other children. Though they may not share their toys or have meaningful interactions, they usually show some degree of interest in other people who are around their age. Since autism can affect social skills, children who have autism often prefer to keep to themselves. They are disinterested in other children and would rather play alone. A child who would rather be alone than interacting with other children may be exhibiting difficulties with social development, which could be a sign of autism.