Original: Her own mother's death on 30 December 1990 inspired Rowling to write Harry Potter as a boy longing for his dead parents, his anguish becoming "much deeper, much more real" than in earlier drafts because she related to it herself.
Simplified: The death of her mother on December 30, 1990 led Rowling to write Harry Potter as a boy longing for his dead parents. His pain became "more deeper, more real" than in earlier versions because she related to it herself.