Attempts to remove books from libraries across the US rose almost a fifth last year, with children’s books featuring LGBTQ characters making up 80% of the most challenged books.

The American Library Association’s annual list of the most challenged books in public, school and academic libraries was topped by Alex Gino’s George, which has made the top 10 every year since it was published in 2015. Objections to the book, about a child who “knows she’s not a boy”, cited sexual references and conflict with “traditional family structure”, with some saying schools and libraries should not “put books in a child’s hand that require discussion”.

Prince & Knight by Daniel Haack. Photograph: Mini Bee

Other books that drew protests included the picture book And Tango Makes Three, about two male penguins adopting an egg to create a family in a zoo, and Last Week Tonight host John Oliver’s parody picture book A Day in the Life of Marlon Bundo, which some concerned readers felt was “designed to pollute the morals of its readers”. Written by Last Week Tonight writer Jill Twiss and “dedicated to every bunny who has ever felt different, the bestseller about a gay rabbit was released just before Marlon Bundo’s A Day in the Life of the Vice President, a children’s book about Mike Pence’s own rabbit by his daughter Charlotte. Pence is opposed to same sex marriage, and Oliver told his viewers: “Selling more books than Pence will probably really piss him off.”

Susan Kuklin’s Beyond Magenta, in which teenagers talk about being transgender, was criticised by challengers for “its effect on any young people who would read it”, while Daniel Haack’s Prince & Knight, a picture book that ends with the title characters getting married, was described by those attempting to ban it as “a deliberate attempt to indoctrinate young children”.

Only two titles in the top 10 had no LGBTQ content: Margaret Atwood’s The Handmaid’s Tale, for its profanity and “vulgarity and sexual overtones”, said the ALA, and the Harry Potter series. JK Rowling’s books were criticised for “containing actual curses and spells”, and for including characters that use “nefarious means” to attain goals.

The library body said that there was a 17% increase last year in the number of books targeted for removal, with 377 challenges in 2019 and 566 books targeted.

In a joint statement, more than 40 free-speech groups including the National Coalition Against Censorship, Planned Parenthood and GLAAD condemned the growing pressure on libraries and schools to remove LGBTQ children’s books.

They pointed out that, in the five years before 2015, the year same-sex marriage was legalised across the US, LGBTQ books never made up more than 20% of ALA’s top 10. Since 2015, they have accounted for at least 40% of the list. This year, the proportion is 80%.

“When LGBTQ stories are silenced in this way, LGBTQ youth and children from LGBTQ families get the message that their own stories – their very lives – do not have value, that they are shameful,” their statement read. “However, reading stories that acknowledge their experiences, in which they can recognise themselves and their families, reinforces their sense of self-worth and helps them overcome the experience of and feelings associated with social marginalisation.”