Though a known opponent of gay marriage and “gender theory,” Pope Francis has unintentionally given his endorsement to a children’s book proposing alternative family styles, including same-sex parents, with a letter from the Vatican Secretariat of State.

The new children’s book called Piccolo Uovo (“Little Egg”) was written by a lesbian woman named Francesca Pardi, who sent a letter along with 30 copies of the book to Pope Francis. The book follows the adventures of an egg through its discovery of different family types including a pair of gay penguins, lesbian rabbits successfully bringing up a family, a single parent hippo, a mixed-race dog couple, and kangaroos that have adopted polar bear cubs.

Ms. Pardi received a letter back from the Vatican acknowledging her note and the books she sent along with it, which she is now publicizing as a “blessing” on the content of her work. The Vatican letter states: “His holiness is grateful for the thoughtful gesture and for the feelings which it evoked, hoping for an always more fruitful activity in the service of young generations and the spread of genuine human and Christian values.”

Pardi told the Huffington Post that she sees the Vatican letter as “an important signal,” saying that “the Pope is opening a dialogue on a subject in which there are conflicting ideas but he does so with a respectful tone.”

In point of fact, Pope Francis never saw the book in question. The Vatican response was a routine letter prepared by the Secretariat of State, which sends out 60,000 such letters every year acknowledging the different messages and gifts that arrive to the Pope.

On Friday morning, the Vatican press office published a clarification, saying that the Vatican’s response to Ms. Pardi was “a simple, pastoral response” that was supposed to remain private. “In no way does the letter from the Secretariat of State intend to endorse behavior and teachings that are not in line with the Gospel.”

“The Pope’s closing blessing is meant for the person the letter is addressed to,” the notice adds, “and does not refer to any teachings that are not in line with Catholic teachings on gender theory. Indeed these teachings remain unchanged, as the Holy Father recently stressed. So a misuse of the letter’s contents is completely out of place.”

Pope Francis has been an outspoken opponent of gender theory, especially when it concerns the indoctrination of children.

In the strongest of terms, Francis has called modern gender ideology “demonic” and compared it to “the educational policies of Hitler.”

Last April 15, at an audience in St. Peter’s Square, the Pope suggested that gender theory is “an expression of frustration and resignation, which seeks to erase sexual differences because it no longer knows how to deal with them.” Removing sexual differences, Francis declared, “is the problem, not the solution.” Acting as if these differences didn’t matter means “taking a step backwards,” he said.

In June, Francis insisted that the “complementarity of man and woman” is essential to marriage, but is under attack from “so-called gender ideology, in the name of a freer and fairer society.”

The Pope has also weighed in on the question of gay adoption, declaring that a child deserves both a mother and a father and that neither is superfluous or replaceable.

“Experience teaches us,” he said, “that to grow harmoniously the human being needs the reciprocity between man and woman. When it’s not there, we see the consequences,” he said.

Follow Thomas D. Williams on Twitter @tdwilliamsrome