However, not everyone in the country approves.
Two fathers go out to buy a guinea pig that costs 17.95 euros in the pet shop. The shop owner gives them a discount of 20 percent. How much must Jan's fathers pay?
In the near future, math books could be posing this question, or one like it, to school kids in the Netherlands. Soon the country's geography and foreign language textbooks will no longer be able to ignore the reality of same-sex parenting in Holland.
Eberhard van der Laan says the country's school system must treat same-sex couples as a normal part of daily life. The 55-year-old father of five children is mayor of Amsterdam, which has been marketing itself as a destination for gay travellers. Now his call has been heard by Holland's largest school book publisher.
"At the moment schoolbooks do not reflect life here," says Frans Grijzenhout, director of the Noordhof Uitgeverij publishing house.
"When a textbook deals with a family going on holiday, for example, the accompanying drawing will show a father, a mother and children. But there are other types of families."
In future, Noordhof's books will reflect the existence of same-sex parents in Holland. The country's schoolbooks already deal with Holland's multicultural society with depictions of Muslim girls wearing headscarves, says Grijzenhout. "In the same way we intend to bring homosexuality to children's attention."
Holland's association for the Integration of homosexuals has welcomed the move. It says the "hetero-normality in schoolbooks" should have done been away with long ago. For a long time the association has been observing a "decline in tolerance towards homosexuals" in Holland.
Homosexuality has a high profile in Holland but the number of attacks on gay men and women is on the rise. Even in Amsterdam homosexual couples have reported they feel less safe than in the past.
Many of the attackers are young men with Muslim immigrant backgrounds. The association for the Integration of Homosexuals says that makes it all the more important for schoolbooks to "show male couples and female couples as completely normal."
However, the Netherlands' Calvinist community, as well as the country's conservative Catholics, has rejected the prospect of same-sex couples in school textbooks.
"Schools should not be forced to accept homosexual emancipation," says the newspaper the Reformatorisch Dagblad, the most important orthodox Protestant publication in Holland.
The Association for Christian Reformed Education has also made it clear no "homo-schoolbooks" will be distributed in its schools.
The idea of making children familiar with same-sex couples is not a new one. Ten years ago the Dutch author Linda de Haan created a stir with the publication of her children's book "King and King".
In the book a gay crown prince refuses to marry a princess but still wants to become king. In the end there is a fairytale wedding between two princes who live happily ever after.
The book was a bestseller in Holland which is known for its tolerant attitudes. But in the US the book's publication was followed by litigation in courts. Some parents called for the book to be banned or at least removed from library shelves. The litigation came to an end in 2007 when a federal judge decided "diversity is a trademark of our nation".