Thaddeus Thurkell was a wizard who had seven sons who were all Squibs. He transfigured them into hedgehogs out of disgust.
2. Seamus Finnigan’s mother didn’t tell his Muggle father that she was a witch until after they married. To quote Seamus, “It came as a nasty shock to him when he found out.”
3. “Blood purity” wasn’t the only gene that Voldemort’s maternal family wanted to keep in the family. As descendants of Salazar Slytherin, they are fluent in Parseltongue—if it meant marrying a cousin or two to keep the ability in the family.
4. A Squib is someone who was born into a wizarding family but hasn’t got any magic powers. They are kind of the opposite of Muggle-born wizards, but Squibs are quite unusual.
5. Draco Malfoy and Nymphadora Tonks are first-cousins by their mothers being sisters. However, they’re not close—Tonks’ mother, Andromeda Black, was cast out of her family after she married a Muggle-born wizard named Ted Tonks.
Cedric Diggory, the doomed Triwizard Tournament contestant, comes from an overachieving family. One of his ancestors, Eldritch Diggory, served as the Minister for Magic in 1733 and founded the Auror program. Unfortunately, he died tragically early in 1747 from Dragon Pox.
7. Luna Lovegood grows up to marry the grandson of Newt Scamander, Rolf Scamander.
8. The first Lucius Malfoy plotted to marry Queen Elizabeth I of England. The Golden Age ruler rejected Malfoy’s offer. It’s rumored that he jinxed her with frigidity in response, explaining, why Elizabeth turned down every offer of marriage before dying single at the ripe age of 69.
9. Gilderoy Lockhart is a half-blood, born to a witch mother and Muggle father. He is also the only one of their three children to inherit magical power, as his two older sisters were both born Squibs.
10. Orford Umbridge was the father of Dolores Umbridge and a squib son. He was an unambitious wizard who worked at the Ministry of Magic as a floor mopper. Orford later became a source of embarrassment for his daughter and would later disappear from sight at his daughter's request in exchange for a small financial allowance.
Draco Malfoy’s paternal grandfather, Abraxas Malfoy, is largely credited with a plot that ended with the first ever Muggle-born Minister of Magic leaving office.
12. Gellert Grindelwald caused the death of many wizards, including the grandfather of Triwizard Tournament contestant and Quidditch pro Victor Krum. When some Durmstrang students thought it was “edgy” to wear the Grindelwald symbol on their clothing, Victor Krum and other family members of Grindelwald’s victims taught them a “lesson” on how “cool” it was.
13. In the 1930s or 1940s, an anonymous publication concerned with preserving the purity of bloodlines within the magical population was compiled, giving a compendium of the truly pure-blood families. They were called Sacred Twenty-Eight.
14. Slytherin student Blaise Zabini is the son of a legendarily beautiful witch. Mrs. Zabini has been married 7 times and her husbands all have a habit of mysteriously dying and leaving her huge amounts of money.
15. Dolores Umbridge, is a half-blooded witch. After her parents split, her Muggle mother took her Squib brother back to the non-magical world and Dolores never spoke of that side of her family again.
The “Hagrid” family name is derived after the Old English word “hagridden,” which means “nightmarish night.” It’s also a euphemism for a hangover.
17. Draco Malfoy’s wife, Astoria, was of delicate health and it was a miracle she conceived their son, Scorpius. This led to rumors that somehow Astoria had gotten a time-turner and went back to conceive a child with the Dark Lord Voldemort himself.
18. Fleur Delacour is one-quarter “Veela” (a fairy-like humanoid magical creature) after her father married a half-Veela witch. To date, it’s still unclear if she and her siblings can transform into harpy creatures like her ancestors.
19. Rubeus Hagrid's father was a wizard and the first husband of Fridwulfa. He was short, not only in comparison to his giantess wife and half-giant son, but by human standards as well.
20. Fred Weasley may have taken Angelina Johnson as his date to the Yule Ball, but it was his twin brother George whom Angelina ends up marrying after the Second Wizarding War that resulted in poor Fred’s death. George and Angelina named their son “Fred II” in tribute
21Harry Potter epilogue
You might remember the Harry Potter epilogue, where we hear of Bill Weasley and Fleur Delacour’s daughter, Victoire, “snogging” Teddy Lupin. Now, remember that Teddy’s mom, Tonks, is related to the Weasleys via their own relation to the House of Black. It’s a distant relation, but fans still note: you don’t need to go far for find wizardly incest.
22. The Weasley's birthed only boys for several generations until their daughter Ginny was born. That seems to have broken the “No Girls Allowed” curse. Most of Arthur and Molly Weasley’s grandkids are girls.