Behind the Arguments Against Gay Marriage

There are many points brought up in arguments against gay marriage. Some bring up the idea that marriage was created for the propagation of children, that the tradition of marriage doesn't apply to gay people, that it is a heterosexual institution.
Lying behind all of these arguments is the basic idea that marriage is the foundation of the traditional family, consisting of a mother, a father and children. It is feared that gay marriage will destroy this structure. These arguments pointedly ignore the fact that the structure of the family has been steadily changing since the mid-50s, as single-parent and diverse families grow in numbers in every country.