In the 1860 US Census for Sunfield, Eaton County, Michigan the family of Betsey (Merritt) Barnum was enumerated as follows:
Dwelling #1460; Family 1439
Betsey Barnum, 46, F, Real property $400, Personal property $40, b. New York
Charles Barnum, 18, M, b. Michigan
Harrison Barnum, 14, M, b. Michigan
Harriet A. Barnum, 14, F, b. Michigan
Polly Barnum, 11, F, b. Michigan
Marilla Barnum, 7, F, b. Michigan
Living one house away was the family of Rachel Barnum. Rachel's husband Willis and Betsey's husband Daniel (both deceased) had been brothers. Both families contained sets of twins, an apparent genetic trait of that line of descent.