first off, all cats are shorthair, so we can ignore that gene, assuming nobody carries longhair.

for color, i was sort of forced into making jingle and bells both cinnamon-- black-base colors are on sort of a dominance scale, which is hard to explain? but in essence, black is dominant to all, chocolate is dominant to cinnamon, and cinnamon is recessive to all. [BB -> bb -> blbl; B is black, b is choco, bl is cinnamon]

so, if either of them were black or chocolate, hazel would be too. full red is out of the question for bells, since that would make hazel a tortie! so, jingle got just regular cinnamon, and bells got to be a tortie to make things a little more visually interesting. being fawn/cream, she could pass either red or cinnamon onto hazelstar, and just happened to pass cinnamon.

the tabby patterns are where it got interesting for me: i didn't want everyone to be classic, but classic is recessive to mackerel, so both parents had to at the least carry classic. my decision was to make one parent [bells] present classic, while the other [jingle] carried it, but i got a teensy bit carried away while drawing jingle, and he ended up spotted, which... makes the genes pretty interesting!

you see, spotted tabby [Sp] is a modifier as stated above, but it only works on mackerel. the classic tabby gene doesn't have the right proteins to present it. this makes the problem of spotted being dominant to non-spotted kind of a non-issue, but means that hazelstar is a spotted tabby under her classic. which i don't mind, that's fun! [jinglehop is SpSp, fully spotted. bells can be anything, but i'm calling her spsp, non-spotted. hazelstar thus ends up as Spsp, spotted and carrying non-spotted!]

white spotting is also pretty curious with these guys. the parents are both low white, but their kit is high white! how is this possible? well, the white gene works in interesting ways; low white is coded as Wsw [white + non-white, i believe], but if you combine two dominant white genes, you get high white [WsWs]! so, jingle and bells simply both passed their Ws genes and had a half-white kitten. [ww is full non-white, if you were wondering]