What is a person's growing up? When the matter is fallen man, whose nature has been damaged by the fall, growing up is usually understood above all as the process of a person's physical formation and development. In the second place people speak of psychic formation and development. Only after that, and not always, do they begin to speak of spiritual formation and development. And by this they usually mean not spiritual development in the proper sense, but something that often substitutes for it in the fallen world: intellectual or aesthetic development, for example.
Meanwhile, spiritual life has no direct relation either to the intellect or to aesthetic experiences. Spiritual life is the relations that bind a person to God and to other people. And it begins in that depth of the human person where the will is born and the breath of life breathes, the breath God gives each of us at creation.
This breath is the foundation of our spiritual life and the only possibility of genuine communion with God. For the breath of life is from God; it is a kind of inner theophany, God's presence in us, which is always with us. And if not for the fall, we would become aware of this presence in ourselves with every year of our growing up: physical and psychic growing up would be accompanied by spiritual growing up.
In the fallen world everything is not so simple: here a person can grow up physically while remaining a spiritual infant, and can live his whole "conscious" life without being aware in himself of the main thing, that breath which connects him with God. But if, even in the fallen world, a person still seeks genuine awareness and does not ignore in himself the gift of God that he has, the breath of life given him at birth, then in the end he contains God within himself according to the measure that God opens to him. The same is true with regard to Jesus, for He too is Man, as we are.
Precisely Man with a capital M, not less than any of us, but more. Because, unlike any of us, His human nature from the very beginning was completely free from original sin. And because His measure of spiritual fullness was absolute from the moment of conception: it was the measure of absolute divine fullness that made Him God-man. But, like every human being, He had to grow up spiritually and physically, becoming conscious within Himself of His measure, the fullness of His own spiritual life. In this respect Jesus did not differ from any other human being. But the results of His spiritual and physical growing up were unique, as was to be expected from the Messiah and the Son of God.