the LORD God formed man out of the clay of the ground and blew into his nostrils the breath of life, and so man became a living being.
At conception two living, material cells combine into one living, material cell. No new matter, nor new life was added, but a new creature has been made. At the moment of conception, the matter and the life in the two parent cells reduces to a single living cell. Therefore, begetting is effectively a reduction of two matters & two life's into one collection of matter with one life. Paradoxically it's this reduction that expands the population.
(1 + 1 = 1)
If we trace back the life of any individual we will see there is an unbroken continuum of reductions of life expanding through all of their ancestors, eventually collapsing back to some single origin somewhere back in time. There cannot be a break in the continuum, because the absence of life is death, and we are not dead organisms. That life is the same life all the time. There is no "new" life added, nor made, nor destroyed: there are just new individual organisms being animated by it.
The life that animates yours and my flesh is the same life that animated our parents flesh, that also animates all human beings, has animated all humans throughout history, and will continue to animate all humans until the end. Your life is my life, is everyone's life, always. Human life is one. The word soul is what use to refer to the life within an individual. My soul is distinct from yours in that it animates my flesh, but it is the same life (human nature) in both of us.
Since we share life, our basic natures are the same - fallen. At our origin, our first parents acted against in pride against truth and in so doing, corrupted the human nature. That trait has is begotten too.
That's why God came to us in flesh - to renew our life and give us a way to escape the corruption of our nature which leads to death. His incarnation created a new life stream without corruption, and his actions in the flesh paid the price of redemption for the rest of us. He offers us this new life through faith and baptism, and nurtures, grows and maintains it with the sacraments.
Just as the reproductive act is the physical manner of begetting a living human organism with a fallen human soul, so baptism is the physical act that begets God's nature in us making us sharers in Christ's new life. Just as food and water are needed for sustenance and growth of the physical organism, so the physical sacraments are needed for sustenance and growth of Christ's life within us.
Amen, I say to you, whatever you did for one of these least brothers of mine, you did for me.