The consensus is that she [Sitamun] was the mother of Nefertiti. Unlike Tiye she was of royal blood and bore the official title "Great Royal Wife." Her children were true claimants to the throne of Egypt. She was probably the daughter of the pharaoh Amenhotep III as well as his wife. Sitamun's sister was called Isis.
In any case, Set was considered a scheming deity who sought to overthrow the reign and sovereignty of his brother Osiris. After Set murdered Osiris he was sought out by Horus (the son of Osiris and Isis) who wounded him in the groin with a spear. Set managed to spear out one of Horus’ eyes but was ultimately overthrown by the god of light.
After Horus was born, he and his mother Isis had to hide from his evil uncle Set who had vowed to kill him. Set was afraid that Horus would grow up and avenge his father's murder. Isis and her son hid in the marshes and swamps of the Nile. Her symbol, the lily, which signified divine protection, was later adapted as a symbol for the Virgin Mary. One day, Horus was badly bitten by a scorpion. His body went limp and he fell into a comatose state. Isis grieved, thinking her son would not recover. This incident in the life of the Egyptian sun god was later adapted by Christian mythmongers.
The ever-important Isis was in fact one of these goddesses known by the title Meri/Mery...That goddesses were beloved or Mery is obvious from an enigmatic spell...that invokes "the Goddess greatly beloved with red hair" or "Her who is greatly beloved, the red-haired"
Isis was a male/female progenitor of knowledge and wisdom, etc. So this was always pictured as a Mother holding a child, which is the same aspect of Mary holding the child.
The World Virgin is sometimes shown standing between two great pillars--the Jachin and Boaz of Freemasonry--symbolizing the fact that Nature attains productivity by means of polarity. As wisdom personified, Isis stands between the pillars of opposites, demonstrating that understanding is always found at the point of equilibrium and that truth is often crucified between the two thieves of apparent contradiction.
At one of her ears was the moon and at the other the sun, to indicate that these two were the agent and patient, or father and mother principles of all natural objects; and that Isis, or Nature, makes use of these two luminaries to communicate her powers to the whole empire of animals, vegetables, and minerals. On the back of her neck were the characters of the planets and the signs of the zodiac which assisted the planets in their functions. This signified that the heavenly influences directed the destinies of the principles and sperms of all things, because they were the governors of all sublunary bodies, which they transformed into little worlds made in the image of the greater universe.
The head of Isis is sometimes ornamented with a crown of gold or a garland of olive leaves, as conspicuous marks of her sovereignty as queen of the world and mistress of the entire universe. The crown of gold signifies also the aurific unctuosity or sulphurous fatness of the solar and vital fires which she dispenses to every individual by a continual circulation of the elements, this circulation being symbolized by the musical rattle which she carries in her hand.
At length Isis discovered that the chest had floated to the coast of Byblos. There it had lodged in the branches of a tree, which in a short time miraculously grew up around the box. This so amazed the king of that country that he ordered the tree to be cut down and a pillar made from its trunk to support the roof of his palace. Isis, visiting Byblos, recovered the body of her husband [Osiris], but it was again stolen by Typhon, who cut it into fourteen parts, which he scattered all over the earth. Isis, in despair, began gathering up the severed remains of her husband, but found only thirteen pieces. The fourteenth part (the phallus) she reproduced in gold, for the original had fallen into the river Nile and had been swallowed by a fish.
While Le Plongeon may be right, the possible historical queen sinks into insignificance when compared with the allegorical, symbolic World Virgin; and the fact that she appears among so many different races and peoples discredits the theory that she was a historical individual.