I dunno; Honestly, roleplayed WELL, that's an interesting point of friction to have. But it needs to be done with knowledge of points 2-5
here; The problem is that there isn't any way to magically make your players better roleplayers.
Uh. Give them some downtime with a loquacious NPC who wants to know this stuff. Take anything you already have of their background and bring it up. Someone has a long lost sister? Maybe someone matching her description turns up. Someone's parent's died when they were a kid? NPC with similar issues who wants to talk.
I dunno. Are your PLAYERS interested in this stuff?