The answer is: 1/3

Luke 15:11-32 - In Jewish tradition, the eldest son typically received a double portion of the inheritance. Thus, in this parable, the younger son would receive one-third of his father's estate. This story illustrates God's unconditional love and forgiveness, echoed in other scriptures like Romans 5:8, which emphasizes God's grace toward sinners.

The Parable of the Prodigal Son is a vivid illustration of grace, love, and restoration, peppered with cultural insights from its time. As we've established, the division of inheritance was governed by customs that typically favored the eldest. In this case, the younger son's one-third inheritance loss underscores his reckless behavior, yet it also mirrors the exquisite balance of justice and mercy found in many Biblical accounts.

The father's reaction—immediate acceptance and joyful reconciliation rather than punishment—is where the heart of the story pulses. It beautifully aligns with concepts found not only in Romans but throughout scriptures, like Micah 7:18, which reflects on the boundless compassion of God. Interestingly, Jewish teaching also emphasizes the concept of teshuva, or repentance, encouraging the idea that redemption is viable for everyone, akin to the son's return to the father.

Furthermore, consider this: traditions suggest that Jesus spoke in Aramaic, and the cultural nuances of the original language are layered with meaning. Profoundly, this parable addresses deep familial bonds and societal expectations of the era—all while giving profound upbeat vibes about second chances.

Lastly, imagine being the first listeners of this parable. They might have considered not just the son’s journey but the father's heart—open and eager for reconciliation—arguably a poignant message resonating for ages to come, encouraging a deeper grasp of human resilience.