Muffy's son's strengths are, obviously, in sports and music. Despite his love of animals, his strengths involving them are rather low, which is rather surprising.
His main interests lie in animals and exercise. Though Muffy wants him to grow up to be intelligent, learning is neither one of his strengths or interests. Instead, he's inclined to grow up to be an athlete unless you influence him another way.
Stages of Life
Note: Your child's personality will differ according to how you've raised him, meaning that your child will not necessarily turn out as listed here. This data is based off of Akie's own experience in the game.
Toddler Stage (chapter 2)
It's hard to keep up with this kid. He's all over the place. He'll go to the barn, the chicken coop, the pasture, the tool shed, the path leading to the spring, etc. He constantly talks about animals, and asks you if you like animals. (You can either tell him yes, no, or that you like him better than any animal.)
He tried to push his luck with his mommy once by staying out in the barn past his bedtime, and Muffy wasn't too pleased. But he didn't learn the lesson: right at the end of chapter 2, he decided to stay up by staying in the kitchen after 9PM. Muffy didn't discipline him for that one.
As regards personality, he must be a lot like Muffy was at that age. He's very outgoing, just like his mama.
Boyhood Stage (chapter 3)
He's still very outgoing and easy to spoil. He and Kate seem to be good friends, they're together fairly often. He's still obsessed with animals, and likes to ask you if running a farm is fun or not. He also started asking me about whether or not I thought I could outrun Wally. Of course, I don't think that would be possible, but it's fun telling him once in a while that his old man could beat a professional marathon man, hehe. ^^; (He didn't believe me, though. Darn.)
He also is developing an interest in art: he says that his mother often praises his work. Maybe a little too much. But Muffy must be enthralled to see him take such an interest in something other than animals. Cody seems to think he has artistic talent, too.
He's very fond of eggs and milk.
Teenage Stage (chapter 4)
He's going through the awkward and rebellious stage, poor kid. The main thing on his mind right now is no longer animals or art, but girls and bodybuilding. He doesn't think he's handsome or strong enough for a girl from the city to like him. (Muffy thinks he must have a crush on someone.) He still likes animals, but thinks that taking care of them is just too much work...
He doesn't smile much, and is a lot harder to please than he was as a child. He will only accept certain things from the ruins and star milk now.
Adult Stage (chapters 5 & 6)
He's more or less reverted to how he was as a child: cheerful and mischievous. He still doesn't seem too likely to take over the farm... and he didn't. He became an artist. I guess Muffy and Cody were on to something when they said he had artistic talent, eh? He still likes to recieve certain things from the ruins and star milk.