Here's what we learned: Dog coat color, shape, and length genetics are based in 16 specific locations of the geneome. The basic color loci are: Agouti Locus (A), Brown locus (B), Dilute locus (D), Extention locus (E), Harlequin locus (H), dominant black locus (K), Merle locus (M), and Spotting locus (S).
Still, this doesn't help the non-scientist understand the amazing differences you see among litter mates... well I recently discovered a little more information about white coats that is very interesting.
Just take a look at the litter from Smilin' Pit Bull Rescue that sweet, adoptable Mama-pittie Onyx delivered:
(Warning, cuteness overload below...)
Onyx, a black short-haired pittie with white spots, had two all-white girls (1 short, 1 long haired), three all-black boys (2 short, 1 long haired), and 1 short-haired brown boy.
But how did a Black dog have pure white puppies? Well apparently the same genes that code for the extension of black and brown pigmentation over the body are present in white dogs, but white dogs are lacking the genes that turn ON the melanin production: ie, inject the hair with melanin from the hair folacle.
[See more pics and learn how you can adopt one of these Adora-bulls, here.]