God merely looks on, letting His laws mete out justice. God remains detached in all beings as the atma . Having given human beings free will, He lets us write our own destiny. We do so and become bound by the chain of karma , which we slowly and painfully work out from birth to birth. It is the past actions of our prior birth that makes us what we are and what we do.
Biologists propound the theory of heridity and claim that it satisfactorily explains human beings.
Similary, the children of the same parents brought up in the same environment do not possess identical personalities. But there is no such thing as change in the universe. Everything is well regulated and follows laws. We see this all around us. Ignorance of a fact does not mean that it does not exist.