“Many homosexuals live together in stable relationships. The time will come when homosexual marriages are recognized,” two Danish psychologists predicted in their honest, controversial, and now-iconic guide to teenage sexuality in 1969. But decades would pass before their prognosis would slowly, painfully begin to come true. In the meantime, those “stable relationships” were denied the dignity of being called a family and forced to conform to the mainstream-normative narratives of what a family actually is.

In the 1980s, writer Lesléa Newman began noticing that same-sex couples were having kids like everybody else, but had no children’s books to read to them portraying non-traditional family units. At that point, women had been “marrying” one another for ages, but true marriage equality in the eyes of the law and the general public was still two decades away, as were children’s books offering alternate narratives on what makes a family. So Newman enacted the idea that the best way to complain is to make things and penned Heather Has Two Mommies (public library) — a sweet, straightforward picture-book illustrated by Diana Souza, telling the story of a warm and accepting playground discussion of little Heather’s life with Mama Kate, a doctor, and Mama Jane, a carpenter.

Heather’s favorite number is two. She has two arms, two legs, two eyes, two ears, two hands, and two feet. She also has two pets: a ginger-colored cat named Gingersnap and a big black dog named Midnight.

Heather also has two mommies: Mama Jane and Mama Kate.

The book, which predated even Maurice Sendak’s controversial children’s story grazing the subject, was unflinchingly pioneering — with the proper social outrage to attest to this status. Not only did it rank number 11 on the American Library Association’s chart of America’s most frequently challenged books in the 1990s, but its impact continued for decades — comedian Bill Hicks, an eloquent champion of free speech, paid homage to it in his final act on Letterman in October of 1993 and it was even parodied in a 2006 episode of The Simpsons titled “Bart Has Two Mommies.”

Despite that, or perhaps precisely because of it, the book lives on as a bold embodiment of Bertrand Russell’s famous proclamation: “Do not fear to be eccentric in opinion, for every opinion now accepted was once eccentric.”

Twenty years later, Newman followed up with the board books Mommy, Mama, and Me and Daddy, Papa, and Me, affectionately illustrated by artist Carol Thompson.

Complement Heather Has Two Mommies with Andrew Solomon’s remarkable Far From the Tree: Parents, Children and the Search for Identity, a moving meditation on how love both changes us and makes us more ourselves, and the impossibly charming And Tango Makes Three, an allegorical marriage equality primer telling the true story of Central Park Zoo’s gay penguin family.