Sirius Black.
It was all about my parents, and their fucked-up belief system. If you'd had to live in a house with Walburga for 17 years, you'd have wanted to run screaming from the house as soon as you could, too. Not like they even gave two fucks about me outside of me being the heir, and all that rot. The better question would be why did I STAY as long as I did?