 in story of doesn't Written her birthday change to 20/12/2008 by her mother

Jason Grace was a son of Jupiter and the mortal Beryl Grace, a TV star of the 1980s, and the younger brother of Thalia Grace (Hunter of Artemis).Jason has few memories of his mother, who was compelled to give him up when he was two, but he remembers enough about Thalia to not be surprised when he sees her again, in "The Lost Hero".Thalia reveals that their mother told her that Jason was dead, and that this was what finally drove her to leave home, after she run away from home and found Camp Half-Blood.