Osteochondrodysplasia question about a rescue cat
SUMMARY: foster kittens of unknown breeding history, I have concerns about possible health issues due to folded ears
hi everyone! 2 years ago, a cat rescue volunteer i help received a call about 3-week kittens whose mom got stuck in a half-open window and died. so i was given the kittens for fostering and neither I nor the volunteer know the specifics of the backyard breeding situation that was going on there. the people just gave us the kittens in a box with no backstory and never asked about them again
now back to the question. i don't know how they were bred but my simplified understanding is that their ears fold = they have the gene that causes health problems. i am looking for some breed specific insight as I mostly have experience domestic short- and longhair cats only. my questions are:
if they are not exactly scottish fold/straight (e.g. their mom was but their dad wasn't), does it still mean the gene is there because 2 of the litter are obviously folds? I've learned that cat breeds don't work the way dog breeds do i.e. they are not a combination of different breeds and their characteristics, they are either a certain breed or not. does it include breed-specific health issues or do those issues still get passed on from the parent of a certain breed? I'm only asking to get an understanding of the possibility of future health concerns, they are all fixed ofc
if they have the gene, does it mean they'll certainly develop joint problems as they age? or is it more of a higher risk kind of thing? are the "straights" at risk too? should they be given any supplements pre-emptively?
including photos for reference. the litter had 2 folds (black and grey smoke), 2 shorthaired straights of the same colorings and one silver longhaired straight. they all have round faces and yellow/orange eyes. I'm mainly including pictures of Brie, the black fold, since she is still in our care and I'm most worried about her. baby pics and other siblings included. Thank u in advance!!!!