Growing up in real filth impacts deeply on children as they get to an age to understand how others around them see it, and respond to it.
Growing up with passive abuse of animals also impacts deeply on children as they start to realize what they are part off, and they too did nothing.
Growing up with intelligent parents, protected by social standing, leaves children knowing their parents are exempt from consequences of whatever is done to them, impacting deeply and silently.
Mold on everything can indicate a damp/ventilation issue, as well as parents who can't or wont stay on top of it. Some seem to think it's just a thing they must live with.
Actual hoarding is a MH issue, and very difficult to treat even when the person is self aware and desperately wants help.
There is a big difference between hoarding and failing to chuck/clear out.
Filthy, unhygienic, and don't throw things out isn't automatically hoarding. But it can mimic the look of chaotic hoarding.
The difference is determined by if the stuff is held onto because of extreme emotional attachment, or just failure to chuck, pass on, dispose, but unbothered if it was all removed for them.
Having hoarding issues doesn't automatically equate to filthy homes. Or homes being out of control, though generally the later is common, but the while it's harder to clean with a lot of clutter, generally it results in the more used areas being clean enough, with hidden or unreachable areas becoming untended, but this can deteriorate.
Not emptying and cleaning cat litter trays is generally a level of care choice rather than entirely overwhelmed. (not including animal hoarders here)
Hoarding doesn't always mean untidy, dirty, squalid, some hoarders are very organized, tidy, clean, and obsessed with keeping things that way.
People have referred to squalor hoarding, what is being described here is very unpleasant but it isn't squalor hoarding. But if they are actual hoarders as opposed to people who fail to chuck, they have the prerequisites to develop into squalor hoarders.
If it is actual hoarding, not caring about hygiene, and protected by status as Dr's the children's situation and repercussions on them, is going to get considerably worse as they get older.