Siblings

Will an Only Child Struggle to Read Others' Minds? Two Twists in the Research on Siblings and Mind-Reading

A study of 109 children aged 3–6 in Wuhan, China found that only first-borns — not all children with siblings — outperformed only-children on theory of mind. And the only-child gap closed after just two weeks of a short language-based intervention, suggesting it was never a fixed limitation.

Is Your Second Child a Slower Talker? What Really Matters Isn't Birth Order

An analysis of 6,163 Norwegian children found that “who is available to talk to this child” explains vocabulary development better than where they fall in the birth order — and older sisters start filling the caregiver role one to three years earlier than older brothers.