There have been other threads on these in the past.
I personally do not herp in California, so I can't talk about exactly where they are found.
The person I got them from has the parents which are wild-caughts. Some were more banded than others and some were extremely dark (which is what I'm after).
I do not believe it is a simple recessive gene, but rather just variable.
He brought over three (was supposed to be 1.2), but ended up being 3.0, so I only got one male. I will be getting a female next year.
He almost looks axanthic/anery (bluish)...but I'm sure that change as he gets older.
Others on here have participated in the Long Beach Cal Kings threads in the past...maybe they will chime in.
Kerby...
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Lonesome Valley Reptiles
www.lonesomevalleyreptiles.com
Specializing In California Kingsnakes