Would you not attribute the simultaneous emergence of these two issues to be due more to a general liberalization in Europe rather than having any cause and effect relationship?
That was my first thought also when I saw the article. It's first necessary to define what constitutes the erosion of the family, then the writer has to show a substantial statistical correlation between this erosion and the general acceptance of homosexual unions. I didn't see the graphs or tables showing how the basic data points to their conclusion-- all we get here is the conclusions with references. The final gap was the missing 'nuts-and-bolts' causal relationship-- just where is the 'harm' mentioned in the title?.
This is a big time hot button issue- and IMHO, these gaps were glossed over because the writer can only preach to the converted, and there is no proof that would ever be accepted by say, Howard Dean's backers. Even if they showed actual electrical shocks leaping from homosexual union law books killing all married persons-- Clinton would still be asking what 'is' is.
The massive homosexual industrial complex knows that they're wacko. That's why they don't call for some new kind of social institution, they want what they do to be called 'marriage' because they know that 'marriage' is better than what they do. But don't ever tell them that, because then they'll accuse you of having latent homosexual tendencies yourself.
Not that there's anything wrong with it.