According to Source Watch, The Institute for Family Studies (IFS) is
a conservative "think tank" which, according to its website, has the expressed mission "to strengthen marriage and natural family and advancing the well-being of children through research and public education."[1] Research from IFS and its employees are frequently cited and published in both conservative outlets such as National Review [2] and more mainstream ones, like the Washington Post.[3]. "IFS is a successor to the Ridge Foundation, through which Bradley and others used to support Wilcox's National Marriage Project."[1] The Institute for Family Studies says that its "commitment is rooted in the social-science fact that children are most likely to thrive when they are raised by their own married biological parents. The underlying premise of its work is that families and communities, freedom and prosperity, and the political order itself -- both at home and abroad -- are all critically dependent upon the existence of a strong healthy, pervasive marriage culture among the citizenry."[4]
I don't entirely understand how this fits their agenda (I would expect a "married heterosexuals are having more sex" narrative), and am not surprised by the results, but also don't really trust the source.