It's obviously Kate Moss's paternal side that's responsible for her looks, because her paternal half-sister is also beautiful and has many features in common with Kate. But neither of them look like their dad! They probably look like a relative or ancestor of his. People can often not look that much like their closest relatives but resemble someone way back, and often that someone is not in their direct line but an uncle/aunt's line. Often two or three generations back. An off-shoot line, I'd call it!
When Kate Middleton was getting married, the papers ran all this stuff about her family history, and there was a photo of a paternal uncle about 2-3 generations back. Pippa looks just like him. And my MIL says that my exH looks just like a deceased great-uncle. My mum always said that I look like a maternal great-grandma. In doing my family's ancestry, I have found photos of my recent ancestors that people have posted online. They look just like my dad and his dad, although they're off-shoot lines rather than direct line.
All this is to say, the off-shoot lines from some way back can appear in your present-day direct line, and I think that that goes some way to explain how good-looking children can have not particularly good-looking parents. Emma Roberts looks SO much like her aunt, Julia Roberts. Another off-shoot line crossing over, looks-wise. They're all gorgeous, of course! Or, like me and my great-grandma, you can look like someone in your direct line back a few gens back.
It works the other way round, too. You can have very good-looking parents and rather average children. Brad and Angelina's first bio child, Shiloh, is stunning, whereas their twins, Vivienne and Knox, are much more ordinary-looking.
I actually find this a fascinating topic, how genes mix and match. I'm convinced there's a "face plate" gene. When people look like a relative, it's often a whole-face thing. Look at how Lisa Marie Presley was a carbon copy of her dad, and how Kaia Gerber is a carbon copy of her mum. Julia Roberts looks just like her dad.