What determines Wurmple's Personality Value?

[FlamingRuby]

So I had a Wurmple ready to become a Silcoon in my Emerald game, and it's daytime right now in my area, so I was expecting a Silcoon to appear when my Wurmple did evolve. It evolves into...Cascoon? That wasn't supposed to happen...was it?

After double checking to see if my game clock was right, (it was) I looked Wumple up in the Pokedex to see what the criteria for a Beautifly was, and read that the Wurmple in question needed to have a personality value of 4 or less.

My question is: How is this personality value determined?

 

[Zera]

Edit: Sorry, read that wrong, -looks like n00b-

 

[DarkSpectrum]

My question is: How is this personality value determined?

It's determined at the time you encounter/catch/recieve the pokemon. Much like the hidden IV values.

 

[Volteon]

if things continue like that, the personality value will be calculated based on the number of threads about this...

Just random, nothing to put much importance.