Because her parents told her to attack (and what to say).
Has Breitbart Gone Full 'Birther' On Ted Cruz?
....."[Donald] Trump, who is closely trailing Cruz in the Republican caucuses in Iowa, has been the lead spokesman for Cruz eligibility accusations. Following in the footsteps of Hillary Clinton, Trump also served as a prominent person questioning Obama's eligibility in 2011.
WaPo and Breitbart have been writing twice the number of stories on the subject of whether Cruz is natural born as those three outlets. Each of the two wrote at least 30 stories on it in the past week, compared to less than 15 stories each from TheNYT, WSJ and Politico."......
Hillary is getting destroyed with younger voters and they think Chelsea is beloved. They really are that delusional.