How did growing up in Hailsham have a negative effect on the characters?

At
first, Hailsham seems like an idyllic environment in which to grow up and get an education.
Later, though, as the truth is revealed, the characters realize they were always living a
lie.

Hailsham seems to be a school where students express their creativity
and idolize their teachers while forming strong bonds with their classmates. When Kathy recalls
her childhood at Hailsham, she seems nostalgic for the innocence of that time. Once the children
"graduate" from Hailsham, they go off to other cabins where they live with other
"graduates" before starting their roles as either "carers" or...