I’ve recoloured all the child and toddler hair in the game (base game + all packs thus far) to match the 6 unnatural colour swatches available to adults purple pastel, hot pink, dark blue, turquoise, green, and white. I was so frustrated by this that I learned to recolour hair just so I could fix it. I just had one problem kids and toddlers don’t have any unnatural hair colours so they couldn’t inherit the unnatural hair colours of their parents. I’m not much of a CC creator but a while back, I wanted to play a perfect genetics challenge in The Sims 4.
Genetic Unnatural Hair Colours for Kids & Tots (Base Game + All Packs)