It's little wonder then that Sharon Osbourne was so overcome with emotion as she watched her brave son take to the dance floor for the opening show of Dancing With The Stars.
The X Factor judge was seen with tears streaming down her face immediately following Jack's debut on the hit show.
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The 27-year-old delivered a playful foxtrot with his professional partner Cheryl Burke. "I want to know how Sharon's feeling right now because momma bear should be so proud of her son," judge Carrie Ann Inaba said as the cameras cut to Sharon, crying tears of joy in the audience.
She was sat alongside Jack's proud wife Lisa, who shared a big hug with her mother-in-law, and her rock star husband Ozzy Osbourne.
Jack decided to take part in the show to help raise awareness of MS following his 2012 diagnosis. "Right now I'm physically able to do DWTS but it might not always be this way, so I don't want to miss this opportunity," he said.
Asked how he was feeling about being on the show, he modestly replied, "We all have our personal problems to overcome."
Jack isn't the first member of the Osbourne family to take part in the dancing competition. HIs sister Kelly competed in season nine of the show in 2009, coming in third place behind Mýa and winner Donny Osmond.
The judges were certainly impressed by his debut. "You can dance. That was fabulous," Len Goodman told Jack, who is a father to 16-month-old Pearl. "You're going to give your sister a run for her money."
Bruno Tonioli, meanwhile, described his performance as "joyful, playful and uplifting".