Well, this is my interpretation of the genealogy of Harry Potter. One fans thoughts on how it could have come to pass.

The True Legacy of Harold James Potter: A thought about how he really became the Boy Who Lived by Chilandra

I own nothing of the following – JK Rowling & the other copyright holders, etc. own them. Just using the characters in a fan fiction story – no money earned.

Hogwarts founders four: Rowena Ravenclaw, Salazar Slytherin, Helga Hufflepuff and Godric Gryffindor.

Each founder chose students to teach magic and once Hogwarts began the students lived in special houses. These houses now bear the names of a founder in truth. Ravenclaw, Hufflepuff and Gryffindor and later the traitor Slytherin.

Each with children of ones own, most were not seen at Hogwarts. Each knew of the others heirs – to protect them all knew. Rowena Ravenclaw a widow and Godric Gryffindor a widower married and had children. Helga Hufflepuff married young and had a daughter before becoming a widow. She later had a son by Salazar Slytherin. The Children of the founders were sent into hiding after Hogwarts was begun.

Each child with a spell to guard them from the truth, and yet not missing ones true nature. Ravenclaws daughter entered the Weasley family a pureblood family. Hufflepuffs children joined the Granger family a muggleborn, but magically special family. The Gryffindor children joined the Potters family a pureblood family. Slytherin children were placed within a family as orphans would be – they were called Malfoy. Named after the special snake guards of Salazar Slytherin.

If a child of Hogwarts comes to school – the sorting hat must not denote ones true nature. Each child will join its opposite house. Ravenclaw=Gryffindor, Hufflepuff=Gryffindor, Gryffindor=Slytherin, and Slytherin=Hufflepuff. Only one way to change it is for the child to ask for another house.

During the years the children grew up and married, etc. However, a legend had been begun by a simple fact. The Hogwarts founders had placed a spell on them and the descendents. Each heir is bound to Hogwarts and must unite to defend it.

The prophecy was lost until the 1960's and was found by Madame Pince in the library at Hogwarts. The prophecy reads: Gryffindor heir of Potter will defeat Slytherin heir by the dawn of the 21st century.

The Dumbledore Family – When Alberforth and Albus were born, it was thought they would not bear the ancestral magic. Albus came into his powers at about ten years old. The Dumbledore family is a direct descendent of King Arthur. Excalibur was lost to the Lady of the Lake but the power given to them by Merlin was still his to use. As the Defender of Hogwarts, he must prepare the latest heirs to follow ones destiny.

The Potters – James and Lilly gave birth to the legacy holder of Gryffindor. Godric Gryffindor in whose blood flows the power of Merlin. Gryffindor himself was a powerful wizard and his heirs guarded a terribly important secret. The secret is that he can wield the scepter staff of Merlin. This artifact is held at the school in a special chamber. His heirs name is in truth: Harold James Merilynius Gryffindor Potter.

The Weasley Family – Arthur and Molly Weasley have the legacy holders of Rowena Ravenclaw. Though, all are in Gryffindor house at Hogwarts, they are in truth of Ravenclaw. They are very true and loyal friends and ones that every one needs. The gifts they bear have not been stated before – They can use magic to heal wounds of magical creation. Some of the gifts include: curse breaking, magical mathematics (not Arthmancy, i.e. chess playing) and some seer gifts. Ravenclaw defenders true.

The Granger Family – Hermione has a muggleborn legacy. As the defender of Hufflepuff she must have power. One child out of five of Granger born bears the gifts of magic. All must attend Hogwarts and most will become the Head Girl or Head Boy of their year.

The Malfoy Family – Based on a group of orphaned children. They were given the last name of Malfoy from Slytherin. They are the defenders of Slytherin. Though, the legacy they hold is in the defense of Hogwarts not of the family true. The defender now must put aside all aspects of house rivalry – the other defenders will take him on. They just need to see his nice side. The defender must not join the side of evil.

Draco Malfoy is the current heir, though his father could have been easily. Sad but true, Mr. Lucious Malfoy had the ability until he joined the deatheaters of Lord V's first attempt at taking over the world.

The Riddle Family – A line of the Slytherin family, it was born of a daughter's marriage in the family. They alone carry on the evil work of Salazar Slytherin.

Apart of the legacy all are entwined. Hence, Harry Potters strange life.

Thank you JK Rowling for giving me this inspiration.