getting good traits into bloodline, help?

[It´sAllAimAssist]

Hi fellow CK3 players.
Could someone give me some pointers on ways to get good traits into the dynasty?

For example I managed to get two kids that have the genius trait.
BUT unfortunatly that was with my second wife after the first one died.
So I already had an older heir who in turn had both a son and a grandson to succeed him.
+ another son who I asume would have become my heir before the genius had I gotten rid of the older one.

Unfortunatly my char died of old age before I had any time to fix the line of succession so the best I had time to manage was marrying the genius girl ( I had a boy and a girl) with one of the small kids in the succesion line so hopefully that trait comes back into the rulers bloodline later on without to bad a sideeffects since they are related.

Maybe it´s a dumb question with a really obvious answers but I´m 20+ hours into the game and there´s still so many things you can do I find by reading the forums I never EVER would have thought of to do or figured out on my own.
ATM I conquered most of scandinavia on the strenght of my champions alone..which I learned from some random forum thread so thanks to whoever wrote about how champions work.

If it matters I am doing a sort of learning game where I start as Bjorn Ironside and am working towards creating the empire of scandinavia +having a ruler with good traits , basically I am just trying to get a understanding of how the games systems work.
So far I´ve gotten to maybe the third successor and created the kingdom of sweden before things feelt like they started falling apart so I restarted a few times. Any tips on any aspect of the game are welcome. =) cheers.

[archonsod]

Generally speaking, if you want to guarantee a trait is inherited you need both parents to have the trait, at that point any offspring are guaranteed to have the trait, with a possibility of the upgraded version.
Actually getting it done is the hard part, particularly without inbreeding. You can use the filter when looking for a spouse to only show those with heritable traits, but you'll likely have a narrow selection between the desired traits and the fertility window (particularly if trying to avoid negative traits).
If you're happy to run the risks of inbreeding then you're kind of heading in the right direction. Assuming you want multiple traits it's usually easier to essentially 'split' the family into two wings, with each focusing on a single trait. At some point you can then marry cousins from both wings to get both traits on their offspring. Rinse and repeat for each desired trait if you want to get multiple traits.
There's a perk in the dynasty tree that increases the chance of inheriting good traits and reduces the odds of negative traits which is likely worth grabbing if you're going down that route.

The other method is to simply only ever marry those with heritable traits. You get less fine control, but the idea is to flood your family with positive traits to the point you're pretty much guaranteed your heirs will get one, even if you're not entirely sure which one.

[Admod, the Equivocal]

Knights/champions are what determine the majority of how good quality your troops are. I normally set my marshall to all ways train my knights/champions. After knights/champions it's men at arms.

If you get tired of chasing armies around and want to wipe the enemy army, investing in light cavalry men at arms is a must.

[CrUsHeR]

Try arranging only marriages with matching traits, ideally for your whole dynasty. I always ignore the prestige hit for that. Only exception is if you start as Tribal and need the initial prestige for MAA.

With most starting locations this probably isn't possible; even the lowborn candidates with congenital traits will only accept a marriage of a certain rank, and there are restrictions from religion and diplomatic range. Plan B is to pick a trait you are not aiming for, they might still resurface in later generation as bonus.

You'll notice that the AI does never aim for congenital traits, so after a few generations of breeding, most of the candidates are from your dynasty.

Inbreeding is mostly dangerous for direct blood relations. So anything like brother-sister or father-daughter must be avoided entirely.
Cousins are okay with at least one pairing of "fresh blood" in between generations. You generally don't want to arrange a marriage if both candidates' parents were already related.

https://ck3.paradoxwikis.com/Breeding#Inbreeding

[It´sAllAimAssist]

good replies, thanks! all of them helpful