Like any other animal (or perhaps more so), Felcan have a very complicated set of genetics that determines the appearance of each individual. I have not described every possible trait here, but I have tried to cover as much as possible without going overboard. First, a simple genetics lesson to get you started. Feel free to skip this part if you already know the fundamentals of genetics.

For each trait, an animal inherits at least two genes, one from each parent. Oftentimes, one trait will cover up all others, and these traits are called
dominant. Traits that are covered by dominant traits are called recessive because in order for a recessive trait to appear the animal must recieve a recessive gene from both parents. Dominant traits are always abbreviated with a capital letter and recessive traits are shown with a lower case letter.

Things do get a little more complicated however because usually there are more than two possible traits. People don't only have blue or brown eyes, for example, they can also be green or gray or black. Felcan traits have varying degrees of dominance and reccessiveness. Traits can be super-dominant or super-recessive, or even super-super-super dominant. The varying degrees of dominance and reccessiveness are shown as follows:

S-S-S-D, S-S-D, S-D, D, r, s-r, s-s-r, s-s-s-r

So super-super-super dominant traits are shown in italics, bold, and underlined, super-super dominants are in only italics and bold and so on. Sometimes a trait will have several genes that have the same amount of dominance. When both are present, it is randomly decided which one will take dominance. The dominant one is always shown first. Also, in rare cases two traits of the same amount of dominance will blend and create a mix of the two. This does not happen often in Felcan genetics.

Now that we have the basics down, here is a chart of possible Felcan traits.
Head - F (feline), c (canine), m (mix)
Ears - Cf (mix), C (canine), f (feline),
t (feline, tufted)
Ear Size - L (large), s (small)
Mane - N (none), l (lion), s (short, hyena-like)
Horns - N (none)
Wings - N (none)
Front Legs - F (feline), c (canine)
Back Legs - F (feline), c (canine) 
Tail -
W (wolf), L (leopard), l (lion), f (fox), p (persian), b (bobbed), d (dog), m (mix)
Coat Type -
L (lion), F (fox), W (wolf), K (cat), P (panther, black), C (cheetah), H (hyena), M (mountain lion), J (jaguar), d (dog), t (tiger), l (leopard), h (cape hunting dog), o (ocelot), c (clouded leopard), k (king leopard), m (mix)
Snow Coat Mutation -
N (none), S (snow), f (faded), w (white), a (albino)
A few notes on the genetic traits: Ears are determined by a size trait as well as a type trait. Ears also have a strange mixing trait that creates a cross between feline and canine ears. The mix is dominant over all other ear genes, including canine. Felcan do not naturally have either horns or wings, but since animal traits can appear over top of any normal Felcan trait (as you will see shortly), these two traits are included in the list. Normal Felcan will always have NN genes for these two traits. Also, note that normally Felcan have matching front and back legs unless an animal trait is found on one and not the other.

The snow coat mutation, if present, will turn the coat white on certain pattern types (wolf, fox, leopard, and tiger). If it is present on any other coat types, there will be no effect. The faded snow coat mutation makes the coat white as well as lightening the color of the markings. The pure white mutation completely bleaches the markings white (no matter what coat type is present) and the albino mutation works much the same way only no pigmentation is found at all (even in the eyes).

The most interesting aspect of Felcan genetics is the fact that each Felcan takes on at least two traits of some non-feline or canine animal. The animal traits, which are designated with an
A# are always dominant over any normal Felcan trait and cover up the normal genetics. Animal traits are passed down from the parents randomly, one from each parent (or sometimes more).

We have also found that the type of animal the Felcan will mimic is determined genetically. Both parents will pass on an animal type and the one that is most easily assimilated in Felcan makeup will become dominant. Here is a chart of most of the animal genes that can be found.
M (mammal) - H (horse/zebra), A (antelope/deer/giraffe), R (rabbit/hare), G (groundhog/squirrel/chipmunk), S (sheep/goat/cow/camel/pig), P (primate), B (bear), R (rodent), F (ferret/weasel/skunk/badger), w (whale/dolphin), s (seal/walrus), a (anteater/sloth/armadillo), b (bat), m (marsupial), h (hedgehog/porcupine/mole/shrew), e (elephant/hippo/rhino), p (platypus/echidna)

B (bird) - S (songbird), R (raptor), T (tropical), O (owl), H (hummingbird), d (duck/goose), h (heron/crane), w (woodpecker), p (penguin), f (fowl), s (small shorebirds), f (large flightless)

R (reptile) -
L (lizard), S (snake), c (crocodilian), t (turtle/tortoise), d (dragon), p (prehistoric)

a (amphibian) - S (salamander), f (frog),
n (newt)

f (fish) - B (bony coldwater), S (shark), t (bony tropical), e (eel), o (other)

i (insect/arachnid) - B (butterfly), D (dragonfly), F (other flying), b (beetle), s (spider/scorpian), g (other ground)

o (other) - M (marine invertebrate), t (terrestrial invertebrate)
Animal types are shown in pairs on the Felcan's genetic chart with first the catagory of animal and then the family. The specific species of animal is put in parentheses after the genes. For example, an alligator Felcan with the recessive shark trait would be Rc/fS. The recessive animal type does not show up at all, but may be passed on to offspring.

Although animal type is genetically determined, offspring's specific animal species is randomly determined, but always something that fits into the dominant catogory. For example, a gorilla Felcan may pass on the primate gene to its offspring. The offspring may be a rhesus monkey Felcan or a lemur Felcan, however. 

There is always room in Felcan genetics for things to be changed or added, so keep checking back to get the latest version of this explaination.