hmmm... so Luffy and Ace aren't blood brothers. I was felt weird about that relationship since Ace came out of the blue years ago, but they look strikingly similar. I wonder if there is blood relation at all such as Roger and Dragon are brothers. However, considering the fact that they would attempt the kill Roger's child, and even the man that built his ship; It's not hard to believe that they would execute his father as well. Perhaps there really is no relation.