For a long time they were claiming our minds were "wired-up" around age 14-15 but eventually decided that 18 yo minds were still re-wiring themselves, basically still able to change their personalties some.

You certainly can still do a lot of stupid things through age 30 so it's a matter of adjusting the threshold, but I could see myself at 21 start the process of "why did I do that"? (Hangover, whatever,) and changing stuff and becoming more tolerant, seeing other person's views etc.

It's been a few years, but reseach shows that the mind may be still wiring at much later age's (60?) but so very low percentage of what it did when you were an adolescent, ie you can still learn stuff.