With MCC you can be on any livespan, they recommend normal, but I've used long, then you go into settings - set life span duration. You set the number of days. So with 2 week seasons, a sim year is 56 days.
In Sweden too YA would start at 18, but with my way of counting years, there is no way to do that and keep the same birthday (which I really like to do, I make it a holiday so I remember birthdays even between their aging up birthdays). That's why I start YA at 20, I figure in the sim world, that's when you finish HS.
For me I need to make elders a lot later than 65, as I think they look ancient. But then I use CAS to make adults look older after 50 (and make sure they can't have kids), and then I use it again to keep elders looking younger.
Oh, I really love your idea! Making the birthday a Holiday, way cool. That way it rolls around, same day, every year. All one would have to do is make a mark on a list for each Sim, to keep track of their 'age, as it were. I'm learning so much in this thread.
Since I play an historic game, I have an unpublished blogpost with all the years, birthdays, important historical events and inventions. That makes it so much easier to keep track. The best part of making the birthday a holiday is that I remember all birthdays even if I play rotationally.
