Ah you see I disagree with all that say that the <PERSON> absolutely hAted <PERSON>. I doubt that, because take in the simple fact that it was NOT their responsibility to raise him. When they first received <PERSON> on their doorstep they could have easily given him up for adoption or sent him to a home when he was slightly older. Instead they CHOSE to raise him and keep him in their household.
I believe that the reason they kept him was because of <PERSON>. <PERSON> loved <PERSON> and so vice versa (the back story of their love is mentioned by <PERSON> in pottermore I believe). <PERSON> obviously knew about magic and he loved <PERSON> enough that he wouldn't leave her after finding out about magic, so we can have the reason to believe that <PERSON> would agree to keep <PERSON> just for <PERSON>.
Now why would <PERSON> want to keep <PERSON>? Now although <PERSON> was quite jealous of her sister, we can't just say that she hated her sister. They grew up together for eleven years and the conflict didn't quite start until the acceptance letter from <PERSON> to <PERSON>. So she loved <PERSON>, and after finding out about her death she had to be heart broken because it was her sister! Her sister whom she grew up with for eleven years! So she had to take <PERSON> in because he was a part of <PERSON>. Now the same reason could go for the awful way they treated him. It reminded <PERSON> too much of <PERSON> so she treated him terribly and so did <PERSON>. 725
I almost get the feel that she wanted to make <PERSON> feel the way she felt when she was a child by giving all the attention to <PERSON>.
Now why did they want him to stay and not go to hogwarts? I agree that it could be the desire for normalcy, but I do think there's more to it and here is my theory: They were protecting <PERSON> from the wizarding world. I mean they had to have grown fond of him throughout the eleven years he lived with them as a non-wizard. No matter how much they hated him, even <PERSON> mentions it in later books. Also aunt <PERSON> knew the wizarding world had cost her sisters life and it pained her, so she may have been trying to protect <PERSON> from the same fate. She didn't want a child, a child who was related to her, to suffer the awful fate his mother had. So she took him in, fed him, clothed him and gave him a place to stay. I do not believe for a second that the <PERSON> hated <PERSON> with all their guys. <PERSON> and <PERSON> were both scared of the wizarding world but they had to take <PERSON> in because he was their nephew. I don't believe that a character can only be bad or not be good, especially in the <PERSON> potter books. Each character has it's good and bad, and it may not always be written with clarity, however it is always hidden underneath their actions. 725