I'm not sure DNA is in the game, the devs said at one point it wasn't.
For good advisors, I usually find someone with a claim, which often means I can invite them to my court.
I marry my daughters to important alliance partners.
That means, as an independent, strong kingdoms that I plan
not to attack.
And other direct vassals of my liege, for easier military conquest inside the realm as a vassal, or strong kingdoms I have no plan on attacking if I plan to attack outside my realm.
Alliances are very important, especially early in the game, when you often are a bit on the weak side.
On that note, it's worthwhile to marry your young daughters to old guys, because you might get lucky, and they have a single son, then the old guy dies, and you can reuse your daughter (invite her to your court again, you have a big positive modifier for it, and you can marry her off again, establishing a new alliance).
Sons I usually marry off to people with great traits, preferably genius, as that
is inherited (for my heir, to ensure a decent batch of grandsons), and the non heirs, I marry off to get the biggest price I can, sometimes both can be arranged (the duchess of Toscana in the 1066 start is both a great selection of traits, young, fertile and has some fabulous lands, which your grandson can inherit, just remember she uses Gavelkind).
Funny how casual around gender issues one becomes when playing CK2
