Bloodline in the Wizarding World

In the wizarding world, bloodline, often referred to as blood status, is a concept that classifies witches and wizards based on their immediate ancestry. It denotes whether an individual descends from magical, non-magical (Muggle), or mixed parentage. This classification is a central element of societal structure and prejudice, forming the ideological basis for major conflicts, most notably the two Wizarding Wars led by Lord Voldemort. While blood status has no bearing on a person's magical ability, the belief in “blood purity” has deeply influenced wizarding history, politics, and social hierarchy for centuries.

The wizarding society is primarily divided into several distinct blood statuses, each with its own social standing and connotations.

• Pure-blood: A witch or wizard with no known Muggle or Muggle-born ancestors. Families who claim this status often go to great lengths to maintain it, sometimes through intermarriage with other pure-blood families, which occasionally led to instability and negative genetic traits, as seen in the Gaunt family. Many extremist pure-blood families, such as the Malfoys and the Blacks, hold the belief that their pure magical lineage makes them superior to others. The “Sacred Twenty-Eight” is a list of supposedly truly pure-blood British families published in the 1930s (Pottermore).
• Half-blood: A witch or wizard with both magical and Muggle ancestry. This is the most common blood status among wizards. This category includes individuals with one magical and one Muggle parent (e.g., Severus Snape), one magical and one Muggle-born parent (e.g., Harry Potter), or two half-blood parents. Despite their prevalence, some pure-blood supremacists still view them as inferior. Lord Voldemort himself was a half-blood but hypocritically championed the cause of pure-blood supremacy.
• Muggle-born: A witch or wizard born to two non-magical parents. Their magical abilities are a natural, though rare, occurrence in Muggle families. They often face significant prejudice from blood purists and are derogatorily referred to by the slur `Mudblood`. Notable Muggle-borns include Hermione Granger and Lily Potter. During Lord Voldemort's second rise to power, the Ministry of Magic established the Muggle-Born Registration Commission to persecute them under the false claim that they had “stolen” magic.
• Squib: A non-magical individual born to at least one magical parent. A Squib is the opposite of a Muggle-born and cannot perform magic. They exist on the fringes of the wizarding world, often facing shame or being hidden by their families. Notable Squibs include the Hogwarts caretaker, Argus Filch, and Harry Potter's neighbor, Arabella Figg.
• Half-breed: A related, highly offensive term used to describe individuals of mixed ancestry between humans and other magical sentient beings, such as giants, Veela, or goblins. Individuals like Rubeus Hagrid (half-giant) and Filius Flitwick (part-goblin) faced prejudice due to their heritage.

The core of Lord Voldemort's ideology and the platform of his Death Eaters was the supremacy of pure-bloods. This belief system promoted the subjugation and eradication of Muggle-borns and the domination of the Muggle world. Families like the Weasleys, who were pure-bloods but did not share these prejudiced views, were labeled “blood traitors.” This bigotry fueled the creation of discriminatory laws and institutions, culminating in the witch hunts conducted by the Ministry of Magic under Voldemort's control.

While blood status does not determine magical power, certain rare magical abilities are known to be passed down through specific family bloodlines.

• Parseltongue: The ability to speak to snakes was passed down from Salazar Slytherin to his descendants, the Gaunt family, and ultimately to Lord Voldemort. Harry Potter was not a true inheritor but gained the ability through his connection to Voldemort's soul.
• Metamorphmagus: The rare ability to change one's physical appearance at will is an inherited trait. Nymphadora Tonks inherited this skill, which was then passed on to her son, Teddy Lupin.

Historically, bloodline has been tied to power, wealth, and influence in the wizarding world. The “Ancient and Most Noble Houses,” such as the House of Black, were old pure-blood families who held considerable social sway and often possessed ancestral homes, vaults at Gringotts, and significant political power within the Wizengamot.

• The Gaunt Family: An ancient, inbred pure-blood line descended directly from Salazar Slytherin. They were fanatically proud of their heritage but lived in poverty and squalor by the 20th century.
• The Malfoy Family: A wealthy and influential pure-blood family who were ardent supporters of blood purity and Lord Voldemort. They used their wealth and status to exert influence over the Ministry of Magic.
• The Black Family: One of the oldest and largest pure-blood families, whose motto was Toujours Pur (“Always Pure”). They were known to disown any family member who did not uphold their pure-blood ideals, including Sirius Black and Andromeda Tonks.
• The Weasley Family: A well-known pure-blood family that was considered a disgrace by supremacists due to their poverty and friendly association with Muggles and Muggle-borns.
• The Potter Family: An old and respected pure-blood family until the marriage of James Potter to the Muggle-born Lily Evans, making their son Harry Potter a half-blood. The Potters were known for their opposition to the Dark Arts.

J.K. Rowling has stated in interviews that the obsession with blood purity in the wizarding world was a deliberate allegory for the racial and ethnic supremacist ideologies of regimes like the Nazis. The terminology used by Death Eaters, such as “pure-blood,” “half-blood,” and the slur `Mudblood`, directly mirrors the discriminatory language used to enforce such doctrines.