Okay fine since no one is going to get it. Every female member of the family is a fat bisexual who looks the same. What does this tell us? Clones. Specifically they're witches, the dad was obviously entranced by their bisexual mom to be a seman bank for her clone daughter army that's why they only have girls, the youngest is being groomed into being the next witch and what do witches do? Eat people, so they're fattening up the dad. You wouldn't notice cause they're all fat and you'd assume they all just have poor eating habits (common in greedy gluttonous bisexuals), however the dad has clearly become a diabetic and now has numb limbs and because he's so far he falls into deep near death comas. And what do cats do when they see sleeping bodies? Check to see if their alive correct and why do they do this? To eat them if they're not. Clearly one night the dad fell into his fat induced coma and had an entire limb nibbled off by the youngest at some point (she's fat, she could eat a whole limb easily) and that's why it's missing, further strengthing the idea that they're all a cabal of cannibalistic witches who are just using the dad as a cover and seman bank.
Bad het relationship.