OMAHA, Neb. -

Billionaire Warren Buffett has received scores of individual requests for help since he announced that he would gradually give away his fortune.
   
So, he turned to his big sister.
   
Doris Buffett and her Sunshine Lady Foundation reviews the letters to find people struggling through no fault of their own and has given the letter writers an undisclosed amount.
   
She has also given away more than $150 million of her own money to help victims of domestic abuse, people with mental illnesses, prison inmates and individuals in the communities where she lives.
   
Northeastern University professor Rebecca Riccio teaches about philanthropy. She says the personal approach Doris Buffett uses and her willingness to consider individual requests set her apart from others.