[hippoman]

There isn't a rational position on opposing marriage between siblings, yet it's still illegal in the US. Of course there are reasons about damage to children, bullying of children, etc but fundamentally people are just repulsed by the idea so they don't want anyone to do it and it's still illegal. Gay marriage is only one of various types of marriage that are unfairly discriminated against. Fortunately gay marriage might now allow a father and son to marry each other, which may help open the minds of the mob.