When a Jewish child assimilates and acts like a member of a subculture of contemporary society, she disgraces the religion for which her ancestors died. The parents are humiliated by her reprehensible act of rebellion. Furthermore, Chazal maintain that her father's position is diminished. He no longer receives the eminence he had previously been accorded. This is a very bitter pill to swallow.
Parents raise a child, assuming that they are doing an adequate job of childrearing.
Suddenly, they are confronted with an out of control situation. In addition to their personal tragedy of losing a child, they are publicly castigated, censured for being poor parents. Nachlas Tzvi cites two apparently contradictory sources in Chazal that seem to address the parents' onus of guilt in the matter. The Talmud Sukkah 56b recounts the story of Miriam bas Bilgah, a descendant of a distinguished family who became an apostate and married a Greek officer. When Chazal heard about this blasphemy, they decreed that the ring in the Bais Hamikdash which was used for slaughtering korbanos, and the little window through which the members of her Priestly family would place their knives, was to be forever sealed.