Well I've got more than a dozen little ones and they seem to be aging properly in game time. I've got mine set to double speed (I have ADD - I can't wait for anything) so the 2 years of nursing takes 120 minutes in real time. They seem to keep aging one year per hour of real time - I'm sure your kids are too but you know what they say about a watched pot! Check your adults to see how fast they're aging - it will probably be at the same rate it's just not really noticable until the Details screen suddenly tells you one of your original villagers is "elderly" (and nursing - what a hoot!).
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"I have not failed, I have simply found 10,000 ways that won't work." Thomas A. Edison