What's up with men changing their mind about kids in their 40s?

I've been reading alot of posts about men who were CF and then changing their mind in their 40s. I suppose they could have always been fence sitters, but what if they were CF and truly changed their minds. I'm a guy myself, so I know that most men want children after they've had their fun in their 20s. I can even see if a man reaches 40 and has never been married but men who say they don't want children in their 30s and then change their minds in their 40s is crazy. We are human so we have the right to change our minds, but our actions will have consequences. If you wait until late 30s (women) or 40s then you will risk miscarriages and disabilities.

What are your thoughts?

How many of you ladies dated any men that changed in their mind about kids at 40?

Do you have any guy friends or relatives that pursued their careers in their younger lives and then settled down with children in their 40s?