Everything is accomplished under the direction of God, the Supreme Person. Material nature provides the body through specific parents, human or animal, but it is under the guidance of the Supreme Soul that it does so. The Lord teaches that being incarnated and conditioned by matter wanders in the material universe on a vehicle conceived by material nature. The Supreme Lord, for his part, is always present at his side as the Supreme Soul. He commands the material nature of giving a particular body to the individual soul according to the consequences of its acts, and the material nature bends to its will. It is not the seed of man that creates life in the womb; in fact, the soul finds refuge in a particle of the male seed, to be then introduced into the womb of a woman. It is then that the body develops. It is impossible to create a living being in the absence of the soul, by simple carnal union. The materialistic theory according to which the soul does not exist and the child is born from the mere material combination of sperm and egg is not plausible and can not be accepted because it is a lie.
The soul is placed by the assistants of God in the sperm that the father releases, which will join the ovum released by the mother, and the union of the two will appear an egg. It is the soul that allows the egg, then the fetus and finally the embryo to develop. Without the soul, no development is possible.
The Supreme Lord says, "Your thoughts at the moment of death determine what your future birth will be".
It often appears that the woman must have been a man in her previous life, a man who, because of her attachment to his wife, has now obtained a woman's body. The man too attached to his wife will naturally think of her at the ultimate moment, so that he will be reborn in a woman's body. Similarly, if a woman thinks of her husband at the hour of death, she will naturally live her next life in a man's body. This is why the holy scriptures give so much importance to the chastity of the woman and to her devotion to man. A woman's attachment to her husband may enable her to obtain a man's body in her future life; however, a man's attachment to a woman will only degrade him, forcing him in his next life to put on a woman's body. We must never forget that coarse bodies of dense and subtle, ethereal matter are only clothes; they represent the shirt and the costume of the soul. Thus, being a man or a woman refers only to the body garment. The soul, by nature, belongs to the marginal energy of the Supreme Lord. Moreover, every living being, as energy, is considered to be originally of feminine essence, that is to say, as an object of pleasure. The body of the man allows more to break away from the grip of the material than that of the woman.