2,232. A Family Who Lineage Is Challenged

Hilchos Issurei Biah 19:19

If the family whose lineage was challenged were Leviim or Yisroelim, one must check an additional pair of women for a total of ten mothers. This is because people of invalid lineage marry Leviim and Yisroelim more often than they do kohanim.

Hilchos Issurei Biah 19:20

It’s only necessary to check the woman’s mothers because when men argue, they disparage one another using defects in their lineage. Therefore, if he was of unfit lineage, it would have become known. Women, however, do not tend to disparage one another using defects in their lineage.