What are the chances of a sim having a midlife crisis?

[Coocoo girl]

I'm not 100% sure this is the right board.  But, errr, this is the board for game mechanics questions right?  On to the question.
My sims in my games haven't been having a midlife crisis lately.  To tell the truth, I've been missing them.  Does it have something to do with how many lifetime happiness points that the sim has when they age up to adult?  Also, what are the chances of a sim getting a midlife crisis?  Again, I'm halfway expecting this to be moved to the generations board, but like I said, I'm not sure.

[Saltypaws]

I think the midlife crisis is random.  I can play quite a few sims and never get the moodlet and then play another game and  as soon as they have their adult birthday, they will get the midlife crisis moodlet.  I don't really think it has anything to do with happiness points, although, I could be wrong, never really thought about that though.  I just know, that not all sims get that moodlet.

[Seabody]

It's not random.

There's a base chance of 10%. The following actions add the following to the chance:

Unemployed - 20%
* Married at 0% of YA - 10%
Never Married - 10%
* Kids at 0% of YA - 10%
* Average Skills at 1 - 10%
Never Moved - 10%
Breaking Up - 5%
Divorce - 10%
Death - 20%
* Average Family Relationship at -100 - 20%
Has Commitment Issues - 10%
Is Ambitious - 10%

I've prefixed actions I don't understand (as in, ones that don't make sense to me) with an asterisk (*). Also, much like Newton's Third Law of Motion, most of these actions have an opposite action. Such as, 0% is literally added to the chances if you "have kids at 100% of YA".

[Ausette]

Thanks heaps for the data, Seabody! I'll definitely be keeping this in mind. I kind of like the Midlife Crises because you get a nice moodlet at the end if you fulfil enough wishes.

I've prefixed actions I don't understand (as in, ones that don't make sense to me) with an asterisk (*).

My interpretation of those actions:

• Married at 0% of YA: The Sim feels like he rushed into marriage way too early. He's insecure about whether or not he made the right decision.
• Kids at 0% of YA: Again, the Sim thinks he wasted his youth by diving straight into having a family. He regrets not having more fun when he was young and had less responsibilities.
• Average skills at 1: The Sim feels like he hasn't achieved enough in his life. He feels inadequate and inept.
• Average family relationships at -100: Poor relationships make stressed-out Sims, who are more likely to doubt themselves and start wondering where they went wrong.

[MoMoll]

I would suppose also that if they never had a previous romantic interest before marriage it would increase the chances to want to have an affair.