What was the cause of hindleys cruel behavior toward heathcliff

Well there are numerous reasons. For starters, he's evil. He's a bully and likes to torture heathcliff for not being like everyone else. Heathcliff has a darker complexion and is a decent young boy, which is another reason for the hatred. He also considers him to be a child born out of sin and out of wedlock which is another reason.

What is the question here