Ageing in games doesn't have to work like it does in real life remember. If you want to age characters to make the plot of the game more plausible, you can. If not for the next 10 years, you don't have to.
Banjo & Kazooie aged two years between games. If they were to appear in another game they'd look much the same age they did in Nuts & Bolts probably despite near 20 years passing since their first adventure. Isn't technology wonderful. Non-linear ageing is great :3
It's all a big Wibbly-Wobbly, Timey-Wimey ball of stuff anyway.