1) Mon, mes, ma, les miens, les tiens, etc, agree with the object, not the owner. That means that you always say "mon père", because fathers are always masculine, even if the child is a daughter. So no, it's not a reference to who it belongs to, and never is in French.
2) Enfants is usually masculine. You can use it in feminine, but it's rare. That means that even if they are daughters, you would still usually say "tiens" in masculine. Similarly, you would say (even though it doesn't make much sense... bear with me) "Ces personnes sont les tiennes" would use the feminine form - tiennes - even if the people in question are male, because "personne" il always feminine.
I hope I'm making sense :)