Most people talk to their babies at least sometimes, but observing families there are huge differences between how much people talk to their babies, how they talk to them, what subjects they talk about, how many different languages they use, etc.
I have a family with a lot of kids. Their neighbour was living with his small family somewhere else for a year where their kids had the sibling and grandparents to talk to.
The younger of two had speech problems.
Then they returned home and the neighbour kids made both of them to talk in a matter of weeks and months.
