Sliced fatty brisket at Killen’s Barbecue in Houston.  (Photo ©Chris Wilkins/Texas BBQ Posse) As expected, our recent story about fatty brisket — when did it become hip? — generated quite a bit of discussion on various social media sites and in emails. The story said that some of us in the Posse were rethinking our preference for fatty, or moist, brisket and ordering more lean brisket. “FATTY! Leave that lean for them skinny jean man bun wearing boys,” Doug Wyman, one of many readers who disagreed with us, wrote on the Posse’s Facebook page. Sam Gwynne, author and Posse member,…