UJM’s question about kiruv with Counterfeit Jews
has been on my mind for more than 25 years.
MY SOLUTION TO THIS PROBLEM:
Every large kiruv organization (NSCY, Aish HaTorah, etc)
should employ a team of highly-qualified genealogists,
to investigate the ancestry of every Baal Teshuvah.
This investigation by expert genealogists should be provided
free-of-charge to every Baal Teshuvah, but the organization
should hold those records permanently, for future reference.
This investigation by genealogists should be done
as soon as possible, even before the Baal Teshuvah
is admitted to the kiruv programs.
Some will be revealed to be Gentiles.
Some will be revealed to be mamzerim.
Some will be revealed to be chalalim.
This makes kiruv more expensive, but it cannot be avoided.
Last but not least, it would be praiseworthy if every Baal Teshuvah
(and every Jew in general) would take a DNA test that proves
that he [or she] really is the son [or [daughter] of his [or her] father.
Without this DNA test, this person could be a mamzer and not know it,
and unintentionally become the ancestor of thousands of mamzerim.