"United States Census, 1870," index and images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MN6D-VW1 : accessed 23 May 2015), Merrill Ingalls in household of Benjamin Ingalls, California, United States; citing p. 1, family 1, NARA microfilm publication M593 (Washington D.C.: National Archives and Records Administration, n.d.); FHL microfilm 545,567.
The Genealogy and History of the Ingalls Family in America: Author: Burleigh, Charles: Publication: Malden, Middlesex, Mass.: Geo. E. Dunbar, 1903: Note: NS340613: Source Media Type: Book: Master Listing Source: Y
It may be possible to confirm family relationships with Merrill by comparing test results with other carriers of his ancestors' Y-chromosome or mitochondrial DNA.
However, there are no known yDNA or mtDNA test-takers in his direct paternal or maternal line.
It is likely that these autosomal DNA test-takers will share DNA with Merrill: