>>11327971It's the prefrontal cortex, and it's at about age 26 for men and 22 for women. Practically speaking, it affects how you reason about your own emotions and motivations across time. Most of the development is done quite a bit earlier though, and you can probably recognize the marked difference between how the average 18 year old reasons about the future and how an early to mid 20s something reasons about the future.
