Here is a research brief produced by US think-tank, the
Institute for Marriage and Public Policy (iMAPP) on the 10th
anniversary of 
same-sex marriage in the Netherlands and the overall state of marriage there.
It provides some food for thought on the possible impact of legalising same-sex marriage on the institution of marriage generally.
There are a few key findings. For example, demand for ‘marriage’ among same-sex couples is far lower than among opposite-sex couples. Also, the institution of marriage is in
worse health than 10 years ago.
According to Dutch statistics, the number of marriages in
the Netherlands has steadily declined since 1999 with a 10pc drop since 2001.
The brief states: “In 2006, Statistics Netherlands reported
that the marriage rate was the lowest since 1945. On the other hand, the number
of registered partners has increased dramatically from 2,000 in 2001 to nearly
10,000 in 2010.”
According to research by Statistics Netherlands, nine in ten
couples plan to live together before marrying and two thirds of
cohabiting couples plan to marry “but keep postponing marriage”.
Meanwhile, the rate of out-of-wedlock births keeps rising, the reports says: “Nearly
one in every ten live babies were born to single mothers last year. Nine
in ten were born to couples living together. Four in ten of the 185,000 babies
born last year were born to mothers who were not married.
It continues: “Many first-born children are born to unmarried mothers
(four in ten) but if the mother has a second or third child she is more likely
to be married. In the decade ending in 2009, the share of unmarried parents
among people in their thirties went from eight to twenty-two percent.”
On the other hand, the brief notes that demand among
homosexuals for same-sex marriage is comparatively low. Just 20pc of same-sex couples are ‘married’ compared with 80pc of opposite-sex couples.
A report by Radio Netherlands quotes Vera Bergkamp, head of
a Dutch gay rights organization, saying that she sees “three main reasons for
the lack of nuptial enthusiasm among gay couples: less pressure from family and
friends, fewer gay couples marrying to have children than their straight
counterparts, and a more individualist, less family-orientated mindset among
many homosexuals”.
According to the official figures, 14,813 same-sex couples
have entered legal marriages in the Netherlands.
The figures suggest that the institution of marriage has
declined among heterosexuals, but cautions that “correlation does not prove
causation”.
Nevertheless, it notes that “[a]t a minimum the data from
the Netherlands does suggest that the hopes of those making a conservative case
for gay marriage that it will strengthen marriage generally and dramatically
increase the stability and fidelity among same-sex couples are likely to be
disappointed”.
