At this point, Stephen had adopted what he thought might be the position of a very classy psychiatrist. Or he was sitting in the chair, leaning kind of vaguely to the left and trying not to look like a gossip. Or maybe that was just the pose of a very lazy person. In any case, Stephen was still quite horrified at what Matthew was telling him, and was therefore trying to pick it apart in the most scientific manner possible.
"Really?" he said when Matthew mentioned how his father had treated him. "Not in the way that he did for her or - oh fuck, I'm sorry. That's not affection. But you know what I mean. Never hugged you or anything?" That seemed unlikely to Stephen, but he figured it would fill in a few gaps in what he knew about Matthew, at least with his very, very limited knowledge of Freudian psychology, most of which was rubbish.
"Of course you don't, she's your sister," replied Stephen, trying to take it easy on his wine, "I mean, sure, objectively it's really, really obvious, but you having raised her and all on top of being your brother - it's only natural that you shouldn't."