He was the last child of Frederick Stainbrook and Agnes Belle Hulings. In the Amboy Journal of 12 December 1877 Lewis is mentioned as a student at Northern Indiana College in Valparaiso, Indiana. The length of his attendance there is not known.

Married Sarah (Sadie) Aird on 31 December 1884 in Lee County, Illinois. She was born 7 February 1867 the daughter of Franklin and Nancy Aird. Lewis and Sadie were the parents of F.J./23 August 1886 (who died young) and is buried in the Ellsworth Cemetery near his Stainbrook grandparents. Two more children were born to the union: Charlotte/28 October 1887, and Forest/10 September 1895.

Sadie died on 12 February 1899. In 1900, the children and their grandmother Agnes were living in Pennsylvania with Lewis sister, Charlotte "Lottie" Fuller. There is some indication that all three of them returned to Chicago, possibly after Lewis married in 1901. Both Lottie and Forrest first marriages took place in the Chicago area.

On 27 November 1901 Lewis Frederick Steinbrook age 41 and Elizabeth McLean age 31 took out a marriage license in St. Joseph, Berrien County, Michigan. They were married there the same day by John C.H. Clair, Justice of the Peace. The brides birthplace is Pennslyvania, Lewis is Illinois. Their residence is Chicago, Cook Co., Illinois. No other information of interest given.

At the time of his mother's death in 1907, the Lee County newspaper indicated that a L. F. Stainbrook and wife, J. O. Stainbrook and wife, Mrs. Van Deventer and Mr. and Mrs. Cotter all of Chicago accompanied the remains to Paw Paw for burial. Lewis residence at that time was 277 Bissel Street.In Chicago City Directory-1909 Lewis a clerk/200 Adams is living with his brother James Steinbrook at 1205 S. Ridgeway. Elizabeth does not appear in the census of 1910/1920. Lewis no longer living with James appears as a boarder in two different locations. In one Lewis states he is single. In the other a widower. It seems more likely that a divorce took place sometime before 1909.

During the years that he worked Lewis was a salesman. He lived for many years at 851 Belden Ave. in Chicago. Lewis was hospitalized three days prior to his death at Cook County Hospital due to arteriosclerotic heart disease. He is in an unmarked grave in this small rural cemetery, probably in the area between F.J.'s grave and that of his parents. His death notice mentions his two children: Charlotte Poland and Forest. Unable to locate any records for a Charlotte Poland. The 1910 census in Oak Park, Cook County, Illinois places Charlotte in the household of W. E. Cotter, married three years, daughter Brownie age two. At an undetermined date a second marriage took place to Hiram Owen Wilson.

Charlotte S. Wilson died in Los Angeles on 28 April 1982.
Forrest Arthur Stainbrook in Barnstable, Massachusetts on 31 October 1987.