I think you're misinformed if you think brain development can be said to taper off in any way over 18 years. That's not what I said, and the advantage you talk

I think you're misinformed if you think brain development can be said to taper off in any way over 18 years. That's not what I said, and the advantage you talked about supposedly does taper off until the child is around 12. (edited for clarity)