Haha, I've been playing this a bit lately and I had some funny sets of circumstances.
I started as a custom count in Ireland with the "wounded" trait and Genius trait as well as midas touched and a bunch of other bad ones to get my age down to 16. Wounded went away like two days after start and I lost the other bad ones pretty quick too, so it worked out well. About 10 years into my reign I finally found a "genius" courtier to wed (age 0, lol), so I invited the father to my court and got betrothed (at age 0!) and wound up tutoring the wife to be as she grew up, giving her the Midas Touched trait too as soon as she came of age. Talk about robbing the cradle, haha.
Anyway, quite a few years later I've conquered most of Ireland and claimed the King title, but all I've had for children is 4 daughters - all of them Geniuses, so i'm getting pretty confident in my pairing two geniuses together to produce a super dynasty. Then I finally have a son, and I'm like "yea! an heir to take all my titles!" and I look at his page... Imbecile, -8 to everything. Oh, good, an imbecile for an heir after having four super daughters.
Luckily I had another son shortly after that, and he ended up being not only Genius but Strong and Attractive too. I was going to give my poor imbecile son a church to remove him from being heir, but it doesn't let you do that - so I had to murder the poor guy. Good thing, too - a few months later my king died at the ripe old age of 66 and left everything to the genius son. The Queen Mother took over managing things and tutoring the heir until he came of age, then he went on to create all the dutchy titles and conquering the remaining counts in Ireland to finally unite the whole island (getting The Great nickname in the process). I've already found him a Welsh six year old Genius Strong Attractive bride to be and invited the father over and now he's tutoring his betrothed too (already converted her to Irish after a mere month and a half), although he's only 14 years older instead of my other king being 26 years older - so I guess it isn't quite so bad haha. Still kinda weird, though.
Funny that you can bring over and raise your own fiance, giving her all kinds of good stats and traits and even your own culture along the way.