Kelly Osbourne is finding it difficult to accept her brother Jack's multiple sclerosis diagnosis.

The pair's mother Sharon has revealed Kelly and her other daughter Aimee have been left stunned by the news of their sibling's condition - which is an autoimmune disease which affects the central nervous system through the brain and spinal cord - and are unsure how to act around him.

She said: ''They look at Jack and they can't quite accept it. He'll always be action man, GI Joe ... they're finding it very difficult to take in. They don't want to treat him differently, that's the last thing he wants.''

The 26-year-old TV star - whose father is wild rocker Ozzy Osbourne - discovered he had MS just two weeks after he and his fiancee Lisa Stelly welcomed their first child Pearl into the world in April after he went to see a doctor following the loss of vision in his right eye.

Jack was then referred to a neurologist who delivered the devastating diagnosis after giving him a series of tests.

He told Britain's HELLO! magazine: ''I saw a neurologist and he did an MRI of my spine and then a lumbar puncture to confirm his suspicions.

''When he said it was most likely MS, I got emotional; I just felt that I was on a real high. I was thinking, 'Why now?' I've always prided myself on the fact that I'm not on any medication; I'm totally normal. I thought, 'It's not really an option for this to be happening right now ... There are four different types of MS, and the other one that I have is relapsing remitting. It's the most Common, but least aggressive form of MS.''

MS sufferers will experience changes in their balance, vision and thought processes.