(Bruno at the dog park)
I decided to learn a bit about the genetics behind the bias:
First of all, many animals have stripes. It is generally agreed that stripes occurred over millions of years of evolution for camouflage purposes, however, dog coats can evolve must faster due to special extra genes that can mutate faster with human breeding.
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).
If a pup recieves "K" and "kbr"- he will be black or dark, and if he recives "kbr" and "kbr" he will be brindle. Also, if he recieves "kbr" and "k" he will be brindle, but he will be light or fawn if he has "k" and "k."
See examples of each color pit bull here.