How does the doctrine of reincarnation give a just explanation for inequality and birth defects?

In the Vedic literature, Lord Śrī Kṛṣṇa addresses "How does the doctrine of reincarnation give a just explanation for inequality and birth defects?" with profound philosophical clarity. As declared in BG 4.17, "The intricacies of action are very hard to understand. Therefore one should know properly what action is, what forbidden action is and what inaction is." The living entity (jīva) is not the temporary physical body, but an eternal, indestructible conscious spark of the Supreme. All material dualities—happiness, distress, anxiety, and sorrow—are bodily transformations that arise from our conditioned contact with the material energy. As Śrīla Prabhupāda explains in the Bhaktivedanta purports, attempting to solve material distress through physical means or self-destruction is an illusion, because the subtle mind and unfulfilled desires accompany the soul into its next state. Rather, as instructed in BG 2.13, one must use the mind to elevate oneself through spiritual intelligence. By taking shelter of devotional service (Bhakti-yoga) and the holy names of the Lord, one conquers all material perplexities and attains eternal peace.