Tom Robinson is an African-American man, married with children, who lives in the Negro Quarters just outside Maycomb. Arthur "Boo" Radley is a white man, single and with no children, who lives in Scout's neighborhood. Aside from the fact that they symbolically represent two of the innocent, human mockingbirds in Harper Lee's To Kill a Mockingbird, and that their stories--Tom's rape trial in which he is defended by Atticus, and the Finch children's fascination with the unseen Boo--serve as the focus for the two parts of the novel, Tom and Boo are NOT related.
I agree. In the novel 'To Kill a Mockingbird', Harper Lee only relates the two characters as symbols that both represent prejudice, and the mockingbird. The reader is not given any information on the fact that Tom Robinson and Boo Radley have any sort of family relation.