Who banned 'Flowers for Algernon'?

Some schools in Pennsylvania and Texas, and in Canada, have banned it at times. The cited reason is some of the strong sexual content when Charlie is exploring his own sexuality and some of his past experiences.

All in all, while the novel - and the original movie - is a bit heavy handed about it, the subject matter is still presented in a tasteful enough fashion that it should pose no threat to the morals of an average youth of 12.

At no point were any immoralities advocated, not by any religious or cultural standard.