这里说的，还不止是IBM的board 而已

Bill had a very close relationship with his mother, Mary, who after a brief career as a teacher devoted her time to helping raise the children and working on civic affairs and with charities. She also served on several corporate boards, including those of the First Interstate Bank in Seattle (founded by her grandfather), the United Way and International Business Machines (IBM). She would often take Bill along when she volunteered in schools and at community organizations.

http://www.biography.com/people/bill-gates-9307520