I think I like it. I think I like her too. And of course she'd be a southpaw, if she's Joe's twin. But how is it that she's so ... self-contained, and he is not? Ah, nature vs. nurture. Now my quibble: I've raised two sons, and I was never anything but grateful they were boys (proof God knows His business, if you will); so Ben makes a big assumption there.
Now for the style and form -- spare, but illustrative, in a nice narrative voice for a mystery. A little understated, a lot endearing, and I'd like to read more by this author, even with different settings and characters, because the writing is clean and enjoyable.