To get a better grasp about how traits are passed from one generation to another, you need to understand how sperm and egg cells are made, and what happens when they meet up first, so here's a good high school biology review of sexual reproduction (the process of meiosis, and fertilization)....

Most animals are diploid, meaning they have two copies of each chromosome (2n). Each individual chromosome can be carrying different genes, maybe even a mutant gene or two ) Meiosis is the production of gametes (sex cells), and ends with cells that have only one of the two copies of each and every chromosome (1n). When these gametes hook-up (fertilization) the egg takes on the chromosomes carried by the sperm and the resulting cell now has two sets of each chromosome (2n), one from each parent.

So why is that important in understanding how BP morphs are inherited? When all these animals reproduce, each parent only gives one of each chromosome, right?. In heterozygous animals (with one mutant gene and one wild-type gene), this may be the chromosome that holds the mutant gene, or it may be the normal chromosome, 50/50 chance. In homozygous animals (mutant or wild type) they can only give one type of chromosome, as both copies are the same.

With recessive traits, if there is a normal copy of the gene present, the trait will not be visable, as wild-type is dominant over these traits, but the resulting offspring will be a carrier for the trait, or a het. With dominant (or co-dominant) traits, the wild-type trait is recessive, and the mutant gene is expressed visibly in the offspring.

If you understand this info, and understand which traits are recessive, or dominant over wild-type (normal), you should be able to figure out the ratios for the resulting offspring of any pair of animals.

Hope this helps, and didn't give anyone flashbacks of bad high school memories.

-Evan