Doc: It's not uncommon for siblings to carve out their own specialty areas as a way to avoid senseless competition for their parents' affection. Her older brother had "the smart one" pretty much locked up, because if you look at it from her perspective, he's so far ahead of her she'll never catch up, and he just blows her away with how much he knows.
So, with "the smart one" taken, she's gone with "the silly one." After all, there's an instant reward when she can make you laugh.
If she was already writing her name at 3, it sounds like the signs were there all along... but what with the older boy as your reference, they might have been easy to miss.
I'd bet she can read a good deal better than she's letting on.
