[brian_cunnie]

IIRC, there were two traits that don't seem to change over the course of one's life: gregariousness, and level of anxiety.

Traits other than those two can change. Classic example: an alcoholic who becomes sober.

[mejari]

An alcoholic that becomes sober is still an alcoholic, they are just in control over their alcoholism.

[brlewis]

A rude person that becomes conscious of the way it comes across to act disrespectfully may still be an rude inside, but if he/she is in control of the disrespectful behavior then I count that as real change.