"But while he thought about these things, behold, an angel of the Lord appeared to him in a dream, saying, “Joseph, son of David, do not be afraid to take to you Mary your wife, for that which is conceived in her is of the Holy Spirit." Matthew 1.20
When one is generated by the Holy Spirit, he is holy, pure, has character, is true, is correct, flee from evil, is perfect in the eyes of the Father, is faithful, loves God, loves his neighbor, forgives, is patient, fears God, he is a new creature, a servant, obedient, his thoughts match the thoughts of God, his word is yes, yes, no, no, and he serves Jesus with all of his heart, with all his strength and with all understanding .
But when he is generated by flesh, nothing of this happens.