In plain words
Before birth there is no world. After death there is no world. So it is only between birth and death that this world comes in. So this bad lies just between two goods.
No one is related to anyone. In bodily terms we may call them fathers, grandfathers, great-grandfathers and grandsons. These are only ties of the body.
"The body is of the five elements; the body must fall, some day; the dweller in the body is free of ill; consider: for the dweller, death and birth and the marks of the bonds of attachment are not; seen truly, that dweller is the God of gods; reflect in the mind: the very form of the Ātma."
What is this body?
"A house of filth, a servant's basket wasting with diseases, a tuber subject to the stir of birth, a thorn-bush that cannot cross the ocean of worldly life, a quiver of arrows. Rise and look; think: is it something we can prize? This body, never trust it as steady, O mind; take refuge at the feet of Hari."
So said Prahlāda. The body is a bubble on water. The mind is a mad monkey. Do not follow this monkey. Follow the citta. Purify your citta, and only then will divinity come to you. That is why Tiruttuṇḍāḷvār: "With a pure citta I am doing Your worship. Rāma, I must win You. I have loved You; take me into Yourself," he said. So the great devotees are noble souls who gave their ideal to the world and met with many hardships and losses, sorrows, blame and reproaches of this kind. Ordinary men bring nothing with them when they come. They do not come wearing even a bit of cloth. When they go, they leave no address. How can such people be our kin? If they are truly yours, why can they not recognise your ties of kinship? But it is only a tie formed by coming together in this world along the way, so each one's birth is his own. Each one's duty is his own. We must develop the humanness that does its own duty and makes life worthwhile.
Bali Cakravarti was the one who taught such oneness, Satya and divinity, drew the people to him, made them happy and ruled over them. So this Onam day is the holy day on which Bali Cakravarti attained Mokṣa. This Onam day is the day on which Vāmana was born.