If we are reborn, why don't we remember our past lives?

memory belongs to the brain and mind of each life; what carries over are tendencies, not details.

Even in Kṛṣṇa's teaching, this is acknowledged: “Many births of Mine and yours have passed, Arjuna; I know them all, but you do not” (Gītā 4.5). Ordinary beings forget.

The tradition explains that what passes from life to life is the subtle body carrying saṃskāras — deep impressions and tendencies — not a diary of events. That is why children show talents, fears or likings that seem to come from nowhere. Forgetting is also seen as a mercy: carrying every past grief, grudge and attachment would make a fresh start almost impossible.

Yoga texts say deep meditation can reveal past births, and some cases of children apparently recalling past lives have been studied, though they remain debated. For practice, the point is not to recover past lives but to use this one well. Whatever came before, your choices now are what shape what comes next.

Source: Bhagavad Gītā 4.5; Yoga Sūtras, Book 3 · Saṃskāras: impressions carried forward

Dharma Q&A — Jyotiṣa, scriptures & modern life · Ask a Jyotishi your own question