Oh you're right about the 25% probability! I wasn't thinking!
There'd be violet eyes/white hair, violet eyes/red hair, green eyes/white hair, and green eyes/red hair.
And then there's that weird thing with the new eye colors added by EA (Patch 5) with shared values.
That is, purple eyes and amber eyes share the same value, so a purple-eyed parent can produce an amber-eyed child. I need to google to check exactly what color that is.
Edited to add: I finally found the amber eye color. In fact, it's right next to the more pronounced violet color and I'd been counting them both as "violet" for the purpose of choosing the heir.
When I hear the word "amber," I envision whale ambergris so was envisioning a more golden color but it looks (to me) like more of a purplish-red. Oh well.
Apparently, if a child inherits the eye color of their purple-eyed parent, there's a 50/50 chance that the child's eyes will be violet or amber.
The same is true for the other four pairs of eye colors, each pair sharing the same value.