Sure, people procreate before marriage, here as over there, but they do manage to perpetuate the species. Homosexuals who are not interested in having children are not going to turn straight and procreate just because an FMA is on the books.
birthrates for western peoples are already imploding. acceptance will lead to increased number of gays through indoctrination in the schools, further depressing formation of families capable of having children. unless you are advocating we setup some programs to match gay married male couples with lesbain couples, so they can "team up" and have kids. maybe you'd like to see a tax credit for that. perhaps not you, but I guarantee you, once we head down this road, the gay groups will petition congress for programs exactly like that.
its valid. It is a whole nexus of things. No marriage makes our values the same and WILL increase the need for welfare as people will have no need to work to keep thier unfamilies together