So actually it is not that brāhmaṇa is made by birth. Brāhmaṇa means, cātur-varṇyaṁ mayā sṛṣṭaṁ guṇa-karma-vibhāgaśaḥ (BG 4.13). By quality and work. Similarly, everything, by quality and work. This is confirmed by Nārada Muni.
- yasya yal lakṣaṇaṁ proktaṁ
- puṁso varṇābhivyañjakam
- yad anyatrāpi dṛśyeta
- tat tenaiva vinirdiśet
- (SB 7.11.35)
Yad anyatra. If the brahminical qualities are visible, manifest, elsewhere. Elsewhere, may be he's śūdra, may be caṇḍāla. Tat tenaiva vinirdiśet. So you, one should accept him as brāhmaṇa. Similarly, if one is born in brāhmaṇa family but his qualities are like śūdra, tat tenaiva vinirdiśet (SB 7.11.35). He should be accepted as śūdra. This is the injunction given by Nārada Muni. Not ordinary person. Tat tenaiva vinirdiśet. And upon this the greatest authority of comment on Śrīmad-Bhāgavatam, Śrīdhara Svāmī, he has commented that janma, birth, is not the chief requisition to become...śama-damādi. One must be qualified with śamo damas titikṣāḥ śuci. Then he should be accepted.