My anecdata agrees. My brother in law's first two kids were born 11 months apart so their developmental stages were pretty synced up, but their third definitely

My anecdata agrees. My brother in law's first two kids were born 11 months apart so their developmental stages were pretty synced up, but their third definitely took a lot longer to start talking. His older brothers just spoke for him and understood what he wanted without him having to speak, so he didn't.