What horror/slasher film is this?

umm i think the plot goes by there being a boy around twelve yeard old who's mum locks him in the basement or something and then she kills her husband cause he couldn't get her pregnant so then she s her kid and she gets pregnant. after escaping the basement, he kills hsis mum, and i think he eats her...? i don't really remember that part exactly. and then he goes on and and kills other people. so yeah, does anyone know what movie this is?