Reviewing the work for The Village Voice, Eliot Fremont-Smith found X: A Fabulous Child's Story to offer "a fable of possibility" supporting "the courage to be oneself and acceptance of individual eccentricity" and wrote that the story's conclusion was "a rather nice verbal joke–with just a whiff of cloning".[6] Publishers Weekly gave the story a positive review, describing the book as "witty, innovative, and sophisticated" and likely to stimulate discussion.[4] The educator Roseanne Hoefel praised Gould's prose and humor for their "keen wit and energy" and described the story as popular among college students in her classes.[7] The English and gender studies professor Nat Hurley praised the book for declining to reveal X's gender to the reader and allowing X to simply exist as ambiguously gendered.[8] Fremont-Smith also described the work as both condescending and authoritarian for the way the story treated the viewpoints of the other parents and the other schoolchildren.[6] He described Chwast's illustrations as "only occasionally ominous".[6]
Some writers have been critical of the extent to which X: A Fabulous Child's Story actually challenges gender roles. Fremont-Smith wrote that the affluence of the Joneses and their ability to provide all the toys X desires suggest that sexual liberation and capitalism are compatible with one another.[6] Jennifer Miller, an English lecturer, described the determination of X's sex via what was presumably a genital examination by the experts as dating the story "by capitulating to the idea that the truth of sex is located on the body".[9] Miller also said that the use of it pronouns for X was a product of an outdated understanding of gender, and might be problematic to modern audiences.[10] Hurley wrote that the determination of the experts that X was well-adjusted "does not force any of the resistant parents to change a single thing about their own rigidly gendered child-rearing practices".[8] The language scholar Paramita Ayuningtyas described the ending of the story as ironic, with the introduction of X's sibling Y suggesting a binary XY sex-determination system that reifies gender essentialism.[11]
