Nonna, the mother of our Saint, was the daughter of Christian parents, and had been very carefully brought up. Like S. John Chrysostom and S. Augustine, Gregory had the inestimable advantage of being reared at the knee of a mother of conspicuous holiness. There were three children of the marriage—a sister, Gorgonia, probably somewhat older than Gregory, who was devotedly fond of her, and a brother, Caesarius, perhaps younger, who was a distinguished physician, and occupied a post of confidence at the Court of Constantinople. Gregory was certainly born at a late period of the life of his mother. He tells us that, like so many other holy men of whom we read both in the Bible and outside its pages, he was consecrated to God by his mother even before his birth. The precise date is uncertain. There are two lines in his poem on his own life which seem to indicate clearly that it took place after his father's elevation to the Episcopate, or at any rate after his ordination to the Priesthood. Speaking of the great desire of the elder Gregory to see his son ordained to the Priesthood, in order that he might have him as a coadjutor and aid to his own declining years and failing strength, he gives the arguments by which the old man sought to persuade him to take upon himself a burden which he dreaded; and among them we find the father saying to the son:  "You have not been yet so long in life as I have spent in sacrifice." And though the Roman Catholic writers on the subject strain every nerve to get rid of the obvious meaning, by ingenious manipulation of the text or by far-fetched interpretations, yet the conclusion remains unshaken, and is supported also by another passage, to be cited presently, that he was at any rate born during the Priesthood of his father. He tells us that he left Athens in or about his thirtieth year,  and also that the Emperor Julian was his contemporary there. Now Julian was at Athens in 355; so that we must place Gregory's birth not earlier than 325; and if we give its natural meaning to the first passage quoted, not earlier than 330, the latest date available for his father's consecration as Bishop. This is not inconsistent with the Athenian chronology of his life, as he certainly spent many years there, and probably did not leave the place till 357.
As soon as the children's age permitted, Gregory and his brother Caesarius were sent to school at Caesarea, under the care of a good man named Carterius, who as long as he lived retained a great influence over the mind of his elder pupil. This is perhaps the same Carterius who afterwards presided over the monasteries of Antioch in Syria, and was one of the instructors of S. John Chrysostom. The following is a free rendering of one of four funeral epigrams written in later years by our Saint in honour of his old friend and tutor:
 Carm. de vita sua, 511.
 Ib. 339.
Reference address : https://www.elpenor.org/gregory-nazianzen/orations-introduction.asp?pg=2