Bhagavad Gita 1.43

By the destruction of our lineage and the pollution of our blood, ancient class traditions and family purity alike perish.

दोषैरेतैः कुलघ्नानां वर्णसङ्करकारकैः।
उत्साद्यन्ते जातिधर्माः कुलधर्माश्च शाश्वताः॥

doṣairetaiḥ kulaghnānāṃ varṇasaṅkarakārakaiḥ|
utsādyante jātidharmāḥ kuladharmāśca śāśvatāḥ||

English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).