If you were feeling lazy, or simply exhausted from making all of those animations for the kids, you could probably reuse the AI for pets on kids. Then simply have a factor (time, wealth, food, etc.) to cause them to grow to adulthood and from there give them all the AI of a regular worker. Possibly add in an AI as a kid that they need feeding, up to you on that one 
OR before they “grow up”, they could be apprentices. Would involve more work, but could be really cool, making them better blacksmiths, for example, more quickly when they grow up and earn a profession. This would provide the upside of better craftsmen but the downside that you would have to predetermine which classes you wanted.