Rupert Murdoch, the 84-year old media baron, will hand over the chief executive reins at entertainment conglomerate Twenty-First Century Fox Inc to his 42-year-old son James, a source familiar with the situation said on Thursday. Fox Chief Operating Officer Chase Carey will step into an advisory role as part of a generational shift at the parent company of Fox News and movie studio behind “X-Men” and other series, the source said, adding that James Murdoch and his 43-year-old brother Lachlan would work as partners.