Then by what you wrote, gay marriage shouldn't be palatable to the state or society, since same-sex marriages usually do not result in natural children with today's technology. So we shouldn't provide any advantages to gay marriages by your argument.

What about "traditional" opposite-sex marriages where children are not produced within the optimal reproductive age window? Should we take away their "advantages"?

> Then by what you wrote, gay marriage shouldn't be palatable to the state or society, since same-sex marriages usually do not result in natural children with today's technology.

Why do you believe creating children is the only social value of marriage? If it figures there at all, it's very low on the totem pole, after all society could simply subsidise rape if that were the point.

I don't. I'm in support of gay marriage. You were giving me reasons why the state/society shouldn't allow sibling marriage.

> You were giving me reasons why the state/society shouldn't allow sibling marriage.

Yes indeed, and then you wrote something completely irrelevant.

How is that irrelevant when you ask

> Why so? That's pretty much what the state does, it provides advantages for situations it wants to see happen more (tax breaks for instance, dispensations or fast tracks, direct monetary grants) and disadvantages for those it doesn't (fines and privation of liberty, mostly). Would you find replacing "the state" by "society" more palatable?

The problem isn't encouraging natural children, it's discouraging the birth of crippled children that has a high likelihood of occurring between closely-related family members producing children together.

Said crippled children are often a drain on society. It's not the children's fault of course, but it's still the case.