I haven't read ACC recently, but I vaguely recall that Vorbretton was implying something regarding muties. Now, I could be completely making this up, but given Barrayar's history of mutie-loathing and all, it's possible that, while Lois may have intended something else, I interpreted it that way.

Also, we know that Barrayar is very not feminist-inclined, and it could be that sort of biology (XY/XX) -- though even that's fungible with top surgeons on Beta Colony.

It's definitely been too long since I read that. The context of that conversation eludes me.