Bill Gates's mom and the chairman of IBM were on the executive committee of the same charity, the United Way.

from https://www.nytimes.com/1994/06/11/obituaries/mary-gates-64-...

     She was later appointed to the board of the United Way of America; in 1983, she became the first woman to lead it. Right Time, Right Place

    Her tenure on the national board's executive committee is believed to have helped Microsoft, based in Seattle, at a crucial time. In 1980, she discussed with John R. Opel, a fellow committee member who was the chairman of the International Business Machines Corporation, the business that I.B.M. was doing with Microsoft.

    Mr. Opel, by some accounts, mentioned Mrs. Gates to other I.B.M. executives. A few weeks later, I.B.M. took a chance by hiring Microsoft, then a small software firm, to develop an operating system for its first personal computer.