TheSilverLining at MTS made a hair genetics mod ages ago - that mod contains four little packages, each of which changes one of the four hair bins from 1 (dominant) to 2 (recessive) or vice versa. I keep the set in my CC hoard for all my not-typical-human-genetics needs, and I was planning to use it in Kulo Seeri to emphasise the fact that, historically, most Nuidya-born Sims have had blonde hair, while red hair is very unusual in KS. (Sena Yuleng's last red-haired descendant was born three generations ago; the only two redheads living in the KS of today, Tania Ursine and Garrett Newson, are technically foreigners.)
The only problem? I wanted three values for my hairs. I wanted black and brown hair - the EA default dominant colours - to be somewhere in between dominant blonde hair and recessive red in Kulo Seeri. Could I tinker with the values in the files?
Yes, I could.
I set TheSilverLining's Black and Brown files from 2 to 1.5, and paired those with the original Dominant Blonde file (no file for red hair, as I wanted it to keep its value of 2). Just to test that it works, I made a random group of three Sims in a testerhood with no CC except these three files.
(Yikes! Well, I did say "no CC"...)
Here are three CAS generated children of the brown-haired man and the blonde woman:
As you can see, every kid these two produced had blonde hair. Next I generated a few offspring for the brown-haired man and the red-haired woman:
And all of their kids came out with brown hair. Success! Want a three-value or even four-value hair genetic spectrum? It's possible!* Just mess around in SimPE and set each bin to whatever values you want.
*Five may also be possible but VT does not know if the custom bin can be tampered with in this way.
So, as I said, I'm not sure if this is already a thing in the Simming community - but it's late at night and I'm excited enough that I got it working to babble about it on my blog :) Anyway, I'd better get some sleep now... tired VT is tired :)