[yeahdude]

Can you name one other kind of marriage that will necessarily get legalized because we legalized same-sex marriage?

Can you name one other kind of marriage that is demonstrably more likely to get legalized because we legalized same-sex marriage?

If there's any kind of slippery slope, it's the slippery slope from man-woman marriage to adult-adult marriage. Well, we've slid down it, and now we're at the bottom.

[Nadya]

Polygamy & Incest

We haven't slid to "adult-adult marriage" yet until the above are legalized across the board. So please don't misrepresent man-man and woman-woman as being adult-adult (or adult - n adult)

Since marriage does not imply reproduction, an incestual couple can refrain from having kids, adopt, use a surrogate/donor, etc. so there is no "but imbreeding" argument. Which is an argument about genetics... Isn't choosing who can reproduce a form of eugenics? We don't stop people with known hereditary complications from choosing to have kids, why should we stop siblings? If they choose to accept the risks, why should society have any say in the matter?

[yeahdude]

Are there any other reasons why incest is considered bad?

[Nadya]

It's a social taboo and imbreeding are the only given reasons of why it is "bad".

Some could argue a failed relationship can lead to issues in a family household but I don't think that has any real merit. Dating a family member's best friend and it going sour can have similar consequences.