And Tango Makes Three, a children’s book about two male penguins who raise an orphaned chick, has topped the annual American Library Association’s list of most complained about books for the third year in a row.

The Association said that there were 513 challenges in 2008, 93 more than the year before. They define a challenge as a “formal, written complaint filed with a library or school requesting that materials be removed because of content or appropriateness.”

Justin Richardson and Peter Parnell’s And Tango Makes Three is based on a real story about a zookeeper who noticed two penguins, Roy and Silo, were trying to hatch a stone, so they gave them an egg instead. The story aims to teach children about difference, but it was accused of being pro-gay, anti-religion and anti-family.

Khaled Hosseini’s bestseller The Kite Runner is also on the list. The book, which has been made into a film, tells the story of two young Afghan boys, and how one betrays the other, after witnessing him being raped by another young boy.

“Books that address same-sex parenting, or same-sex relationships, are particularly prone to challenges in the US,” said Deborah Caldwell-Stone, deputy director of the American Library Association’s office for intellectual freedom. “In the case of And Tango Makes Three, there are many parents who believe it inappropriate to teach children anything at all about homosexual relationships, even in the form of a picture book about a true story.”

The top ten most frequently challenged books of 2008 were:

1. And Tango Makes Three by Justin Richardson and Peter Parnell.
Reasons: anti-ethnic, anti-family, homosexuality, religious viewpoint, unsuited to age group.

2. His Dark Materials trilogy by Philip Pullman
Reasons: political viewpoint, religious viewpoint, violence.

3. TTYL; TTFN; L8R, G8R series by Lauren Myracle
Reasons: offensive language, sexually explicit, unsuited to age group

4. Scary Stories series by Alvin Schwartz
Reasons: occult/satanism, religious viewpoint, violence

5. Bless Me, Ultima by Rudolfo Anaya
Reasons: occult/satanism, offensive language, religious viewpoint, sexually explicit, violence

6. The Perks of Being a Wallflower by Stephen Chbosky
Reasons: drugs, homosexuality, nudity, offensive language, sexually explicit, suicide, unsuited to age group

7. Gossip Girl series by Cecily von Ziegesar
Reasons: offensive language, sexually explicit, unsuited to age group

8. Uncle Bobby’s Wedding by Sarah S. Brannen
Reasons: homosexuality, unsuited to age group

9. The Kite Runner by Khaled Hosseini
Reasons: offensive language, sexually explicit, unsuited to age group

10. Flashcards of My Life by Charise Mericle Harper
Reasons: sexually explicit, unsuited to age group.