Benedict XVI is never wanting for clarity. In an introduction to a new book:

Benedict XVI said it was important to observe that the concept of “same-sex marriage” is “in contradiction with all the cultures of humanity that have followed one another up to now, and thus signifies a cultural revolution that is opposed to the whole tradition of humanity until today.”

He pointed out that there is no doubt that different cultures have varying juridical and moral conceptions of marriage and the family, such as the profound differences between polygamy and monogamy.

But he emphasized that the basic community has never questioned the fact that the existence of the human being in its male and female forms is ordered to procreation, “as well as the fact that the community of male and female and openness to the transmission of life determine the essence of what is called marriage.”

(My emphases)