Family member starting location

[hrvojej]

You mean the same city their parent came of age in, or the same city that their parent is currently located in?

In my experience:
The same city that the parent, father-in-law, or adopter is in, or is closest to if he is out in the field. Only if the father is dead they pop up in the capital, and I believe this is also the case for son-in-laws whose father-in-law is dead. Perhaps the crusade messes up things though (edit:or perhaps not if you hadn't taken Antioch before he came of age - then Scotland could be the closest).