Take princes Harry and Wills, for example. The former is dashingly handsome, while the latter has been, err, blessed with his father Prince Charles' distinctive looks.
Then you've got Ben (hottie) and Casey (nottie) Affleck, Nick (hottie) and Aaron (nottie) Carter, and Brad Pitt (hot, hot hottie!) and his younger brother, Doug (nottie).
Mind you, being a less-hot version of Brad Pitt is still pretty hot to us!
Check out our slideshow of sexy Hollywood spunks and their not-as-genetically-blessed bros.