One apple spoils the barrel

एकेन शुष्कवृक्षेण
दह्यमानेन वह्निना ।
दह्यते तद्वनं सर्वम्
दुष्पुत्रेण कुलं तथा ॥

A single burning dry tree leads to an uncontrolled forest fire that burns the entire woods. Similarly, a wicked son causes embarrassment, dishonor and infamy to his entire family.

One apple spoils the barrel.