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How can you tell when your frontal lobe is fully developed?

While the brain grows to 90% of its size by age five, the frontal lobe continues to mature well into the mid-20s, affecting key executive functions. This prolonged development is why we see a gradual shift from impulsive, risk-taking behavior in teens to the more rational and stable actions typical of young adults. But since there is no magic switch, the real indicator of a fully developed frontal lobe lies in the observable changes to your behavior and cognitive abilities over time.