This was over on Fancast

This season on ‘Criminal Minds,’ it appears that JJ and Emily have switched roles in regards to how they’re responding to the cases they’re taking. In the past, Emily was more controlled/compartmentalized and JJ more emotional. Is the switching of roles intentional or perceived? – Shawn

Responding on behalf of the show he created, Ed Bernero says, “I’m not sure we agree that their roles have changed. JJ, though she has always been ‘tougher’ than anyone else, was always the character more apt to display compassion, because it is part of her job to do the most interaction with family and with stressed cops. As far as Emily, we think she’s still the tough, controlled cop she always was, though as an only child she’s becoming much more used to operating within the family and caring about other people – i.e. the team.” Sounds like “perceived” to me, Shawn.

I'd have to agree on 'perceived'. I haven't seen a switching of roles. In fact, I've seen a lot of similarities among the ladies for some time now, unlike the fellas on the team. I think both women have had a lot happen on the job. Emily was probably a lot better at compartmentalization in the beginning (Revelations) because she didn't go through half the stuff she's been through since joining the team.

And hey, that answers any question about whether Emily has any siblings! =)