Hari-bhakti-vilāsa gives definite instructions that by proper initiation by a bona fide spiritual master one can immediately become a brāhmaṇa. In this connection he says:
yathā kāñcanatāṁ yāti kāṁsyaṁ rasa-vidhānataḥ
tathā dīkṣā-vidhānena dvijatvaṁ jāyate nṛṇām
“As bell metal is turned to gold when mixed with mercury in an alchemical process, so one who is properly trained and initiated by a bona fide spiritual master immediately becomes a brāhmaṇa.” Sometimes those born in brāhmaṇa families protest this, but they have no strong arguments against this principle. By the grace of Kṛṣṇa and His devotee, one’s life can change. This is confirmed in Śrīmad-Bhagavatam by the words jahāti bandham and śudhyanti. Jahāti bandham indicates that a living entity is conditioned by a particular type of body. The body is certainly an impediment, but one who associates with a pure devotee and follows his instructions can avoid this impediment and become a regular brāḥmaṇa by initiation under his strict guidance. Śrīla Jīva Gosvāmī states how a non-brāhmaṇa can be turned into a brāhmaṇa by the association of a pure devotee. Prabhaviṣṇave namaḥ: Lord Viṣṇu is so powerful that He can do anything He likes. Therefore it is not difficult for Viṣṇu to change the body of a devotee who is under the guidance of a pure devotee of the Lord.
Ref >> Srila Prabhupada Vani.