भागवत - सुतो अहितः

परोऽप्यपत्यं हितकृद् यथौषधं
    स्वदेहजोऽप्यामयवत् सुतोऽहितः ।
छिंद्यात् तदंगं यदुतात्मनोऽहितं
    शेषं सुखं जीवति यद्विसर्जनात् ॥

- भागवत

paro api apatyam hitakRud yathA auShadham
    svadehajaH api amayavat suto ahitaH ।
chindyAt tadangam yad uta Atmano ahitam
    sheSham sikham jIvati yad visarjanAt ॥

- bhAgavata

Even if he is someone else's son, if he helps you (in time) like a medicine then he is to be considered one's own. On the other hand, if your own son is causing troubles then you should cut ties with him. Just like cutting a problematic body part will relieve the rest of the body from pain - rest of the family will be relieved if you cut the ties with such a bad child.

- Bhagavata