SB 6.15.7
dehena dehino rajan
dehad deho ’bhijayate
bijad eva yatha bijam
dehy artha iva sasvatah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
As from one seed another seed is generated, O King, so from one body [the body of the father], through another body [the body of the mother], a third body is generated [the body of a son]. As the elements of the material body are eternal, the living entity who appears through these material elements is also eternal.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
From Bhagavad-gita we understand that there are two energies, namely the superior energy and inferior energy. Inferior energy consists of the five gross and three subtle material elements. The living entity, who represents the superior energy, appears in different types of bodies through these elements by the manipulation or supervision of the material energy. Actually both the material and spiritual energies — matter and spirit — exist eternally as potencies of the Supreme Personality of Godhead. The potent entity is the Supreme Person. Since the spiritual energy, the living being, who is part and parcel of the Supreme Lord, desires to enjoy this material world, the Lord gives him a chance to accept different types of material bodies and enjoy or suffer in different material conditions. Factually, the spiritual energy, the living entity who desires to enjoy material things, is manipulated by the Supreme Lord. The so-called father and mother have nothing to do with the living entity. As a result of his own choice and karma, the living being takes different bodies through the agency of so-called fathers and mothers.