|1900 U. S. Census, New Mexico, Bernalillo County, Old Albuquerque, Enumeration District 10, Sheet 12 B.|
This 1900 household is headed by Menhard Albers, an 1868 Illinois native. Listed as a boarder in the home is John Goldenstein, an 1875 native of Germany. What is not stated in the census and is only known because this family has been well-researched, is that John Goldenstein is a first cousin once removed of Menhard Albers. Menhard's mother and John Goldenstein's paternal grandfather were sister and brother.
Of course the census does not always tell you that. But those boarders should not be overlooked.