Will genetics still work with cc hairstyles in Maxis/EA colors only?

Hair that comes in the 18 EA colours that is "maxis match", that is, it matches the clay aesthetic of the game, usually doesn't affect genetics.

This is an example of a Maxis match hairstyle
https://i.imgur.com/c5XiMmX.png

Her son was able to inherit that particular shade of brown
https://i.imgur.com/bGb7Apg.png

So to answer your question, yes. By default, maxis match should work the way you are wanting it to with regards to inheritance and genetics.

Outfits should not affect genetics.