What's in a name?

Overheard in the library:

First man, "Yep, I have two kids, Hudson and Emerson."

Second man. Blank stare. Long pause, "Are they both boys or both girls?"

First man, "Emerson is my daughter and she is the oldest and Hudson is my son and he's two years younger."

Second man - Nods and smiles, wanly.