There were a couple of things mentioned in the previous story set about the transition between childhood and adulthood (the teen years) and what things they are allowed to do, and when. Like when Reid mentioned that he wouldn't be allowed to rent an apartment until he was 19. These are rules I've made up for my worlds, in this fictional future, based partly on RL laws and also partly on what makes sense for my game.
For example, the age of majority needs to be 19 in my game rather than 18 or some other number, because I need high school aged sims to be able to use the in-game school system and many of my teenagers will turn 18 before they graduate high school.
Another example is that children and babies can be left at home in game, unattended, without any consequences. That just doesn't make any sense to me. So, even though my sims don't need a babysitter, I make them arrange one (like here) for the sake of realism.
So if you were a young sim living in my world, these would be the laws that governed your growing up.