[livi]

I think one need to acknowledge the difference between more or less inherited personality traits - in my book stable over time - and behavior. The latter will naturally be changeable according to will force/need/circumstances/age etc.

This will make a person seemingly changing in the eyes of the beholder, but it does not change the variance of his inborn personality traits.

There is a semantic problem here, making it difficult to know for sure we are actually meaning the same thing in terms of what is changing and what the origin of personality and behavior consists of.