Aging for "Active Household only" works not as expected -- an experiment in rotational gameplay

I left my sim alone for about 2 weeks or so (in game time) and I came back to another child! I really don't like my sims doing anything while I'm not playing them because then they don't do their work responsibilities and stuff. Is there any way to completely freeze them while I'm not playing them? I never had this problem with sims 3...