the continuing perception that comics are for young people, and as such should be "universalised" rather than targeting specific groups, and hence are heteronormative, failing to provide characters that LGBT-identifying young people can identify with. Other educational comic books such as the Swiss Jo (1991) also exclude explicit reference to homosexuality (as well as drug-taking and prostitution), in spite of their target audience being older. In 2010 Northwest Press began publishing LBGTQ themed works, focusing primarily on graphic novels and anthologies of artists' shorter works. No Straight Lines, a 2012 anthology published by Fantagraphics Books edited by Justin Hall, presented an overview of comics by and about lesbian, gay, bisexual, and transgender people since the 1960s. Mainstream American comic books Mainstream comics have historically excluded gay characters, with superhero comics in particular and the publishing houses Marvel and DC, the two largest publishers in the genre, and were criticized for their lack of inclusivity. Transgender characters have likewise been under-represented, although the common storyline of a superhero having their sex changed by magical or technological means has been regarded as an oblique reference to transgender and transsexual issues. British comics author Neil Gaiman has said that he included transgender characters in his works, such as Sandman, in response to the lack of realistic representation of such people in comics. Queer theory analyses have noted that LGBT characters in mainstream comic books are often shown as assimilated into heterosexual society, whereas in alternative comics the diversity and uniqueness of LGBT culture is at the forefront. Mainstream comics have also been labelled as "heteronormative", in comparison to "integrationist" alternative comics. Censorship and criticism For much of the 20th century, creators were strongly discouraged from depicting gay relationships in comic books, which were regarded as a medium for children. Until 1989 the Comics Code Authority (CCA), which imposed de facto censorship on comics sold through newsstands in the United States, forbade any suggestion of homosexuality, and LGBT characters were excluded from comics bearing the CCA seal. The CCA itself came into being in response to Fredric Wertham's Seduction of the Innocent, in which comic book creators were accused of attempting to negatively influence children with images of violence and sexuality, including subliminal homosexuality. Wertham claimed that Wonder Woman's strength and independence made her a lesbian, and stated that "The Batman type of story may stimulate children to homosexual fantasies." Storytellers subsequently had to