Of the eight Harmon children, two became active Seventh-day Adventists: Ellen and her older sister Sarah, whose son was hymn-writer F. E. Belden. Both of Ellen White's parents died Sabbathkeepers and believers in the Advent message, as did her brother Robert, who died a little more than 10 years before the church officially organized in 1863. Mary, six years older than Ellen, considered herself a Seventh-day Adventist, although there is no record of her formally joining the church.

Ellen White maintained close relationships with her remaining three sisters and older brother, John, corresponding and visiting with them, and sending them copies of her books and subscriptions to Adventist journals. At one time she wrote of her sisters, "Although we were not practically agreed on all points of religious duty, yet our hearts were one" (Review and Herald, Apr. 21, 1868).