Race v sex preference

I found this in a same-sex discussion on a blog:

Okay, no one has stepped up (that i've noticed) to address the whole analogy of the current gay marriage movement to the civil rights movement and the bans on interracial movement.

The analogy doesn't work for one simple reason. Race is purely a social construct. Sexual preference (according to the establishment view) is innate to an individual, and consequently not socially constructed (granted it may be socially influenced, but that is society's imposition of its norms, not the realization of the individual's unimpeded desires). Therefore, the two situations are quite distinct. The laws on interracial marriage sought to establish bans that artificially limited marriage based upon a social construction. Not allowing gay marriage, explicitly or implicitly (depending on the laws), bans certain behaviors based upon a real inherent difference.

This is amazingly stupid. Race is innate, and not a social construct. Sexual preference is probably not innate. There is certainly no genetic or other objective test for identifying sexual preference. Some states once had marriage laws that discriminated based on race, but no state marriage laws discriminate based on sexual preference. (The restriction is that the couple have opposite sexes, but says nothing about their sexual preferences.)