Robert Williams Wood was born on May 2, 1868, in Concord, Massachusetts, United States to the family of Robert Williams Wood Sr. and Lucy Jane Davis. His father, who was born in Massachusetts in 1803, grew up in New England, and was a physician in Maine until 1838. Then he went to the Hawaiian Islands, where he stayed until 1866 as a physician and pioneer in the sugar industry, after which he returned to New England. He was active in the American Statistical Association. From his childhood Wood, showed an absorbing interest in all sorts of phenomena in natural science, and he soon started finding out for himself what made things work by trying experiments of his own.