(CNN) – She is the sister of billionaire investor Warren Buffett, and like her brother, Doris Buffett is a big philanthropist. To date, she's given away $100 million and she says she won't stop until that last check bounces. Doris Buffett joined us on on Tuesday's American Morning to talk about her Sunshine Lady Foundation and the new book about her, "Giving It All Away – The Doris Buffett Story."