That event happens as a way of trying to fix a bug with children's stat balance. The normal range of stat scores is supposed to be from 0-10, with anything above 10 supposed to be indicating especially exceptional talent (like prodigy/genius level).
Unfortunately, with the bug it became real easy for everyone in the game to have scores way over 10, sometimes hitting in the upper 20s. The problem is that when everyone in the game has stat scores this high, the balance of the game gets thrown horribly out of whack. With massive intrigue, you don't need to rely on vassals, with massive stewardship, money never becomes an issue and you can field giant armies, and so on with other problems with the other scores. The event tries to bring the game back into proper balance.
As to female succession, I believe if you enable that inheritance law, your daughters will be able to inherit if you have no legitimate sons.
And no idea what the New Traits Mod is, sorry.