Some people use CJSI to
determine if a surname is Jewish. The fact that you find a surname in
this index does not necessarily mean that a given surname is Jewish.
This occurs for three major reasons:
- Jews and non-Jews share surnames. The third
most common Jewish surname in the United States (after Cohen and Levy)
is Miller. Clearly Miller is both non-Jewish and Jewish.
- Intermarriage and conversion. The fact that
the surname McKenney appears in CJSI does not mean necessarily that Jews
bore this name. One source , the Family Tree of the Jewish
People, is a
database of family trees developed by Jewish genealogists. But these
also include non-Jewish branches of families.
- Nature of database. Some of the databases named
are predominantly Jewish but do contain
non-Jewish individuals. An example is the Russian Consular Records
database of people who transacted business with the czarist consulates
in the United States.