Health and Fertility are still inherited, I believe.
I prefer this system, it lets me just find any young, fertile wife, or maybe search for one with high stats, but I don't have to bother trying to find one with high base stats anymore.
How childrens stats are determined strikes me as something that would be hardcoded, and can't be changed without also changing a lot of other things back to vanilla and breaking the game.
If you want to end up with superhuman rival rulers (or your own), i'd recommend consang (and editing consang for your rivals should be trivial). At least they'd have a high martial skill. Plus more land, if there's a high intrigue guy down the line at some point, since sons' land gets recycled back to the ruler upon inheritance.