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I play the PC version, but maybe I can help you.
Sims such as the Repoman, Maid, Fireman, Repairman, etc. are known as Non-Playable Characters, or NPCs. I've never heard of them buying houses and having babies, though. Also, in the PC version, we have Story Progression, which allows new families to move to town. It's quite possible that the console version of the game doesn't have Story Progression. I'd be interested to hear what others have to say about it.