Robert Wintemute, professor of human-rights law at King's College, London, thinks so. “The long-term trend is toward the universal acceptance of gay marriage,” he says. “It's just like the vote for women. It begins in one liberal country and then spreads around the world.” Maybe—but if such a trend exists in Islamic states where homosexual acts are seen as a sin, often punishable by death, it is hard to detect.
The question of what the long-term trends are in terms of allowing gay marriage is an interesting one. Certainly in some regions there seems to be a trend towards acceptance. But in others there is clearly not. Here is a rough breakdown by various countries/region:
Western Europe/EU Members/Canada/U.S./Australia/NZ: There is a definite trend towards acceptance. In 30 years, I would guess that gay marriage will be legal in most areas in these countries. The one sub-region where this is not the case is certain areas of the U.S. that have constitutionally prohibited it (largely in response to a court ruling in Massachusetts that allowed it).
The Islamic World: No movement towards acceptance of gay marriage at all.
Asia: There are a few enclaves where gay marriage, and gay rights more generally, are more accepted than others, but there does not seem to be a strong trend toward it. It will be interesting to watch China in this regard. They are such a massive presence that any steps they take will be very influential.
Africa: South Africa has taken the lead in accepting gay marriage. It is not clear whether other countries will follow. The influence of South Africa may bring a handful of others along.
Latin America: There seem to be a few urban and other areas where homosexuality and gay marriage are becoming more accepted, but the movement is just in its infancy.
So is there a trend here? In some parts of the world, a trend towards allowing gay marriage seems fairly clear. But worldwide the issue is more uncertain. Much of the world, including Africa, East Asia and Latin America seem to be at a crossroads. There are groups pushing for gay marriage, but they face a very skeptical populace.