Mozart was a genius but most child prodigies do not grow into elite adults.

[](https://boingboing.net/2026/02/19/new-research-debunks-the-brain-at-25-factoid.html "The "brain isn't done until 25" factoid is based on a funding cutoff")

You've seen the claim on TikTok, in parenting forums, and in roughly a million Instagram infographics: "Your brain isn't fully developed until you're 25." It's the go-to explanation for everything from bad relationships to impulsive…