Yep, not every country deals with incest, be it sexual or only legal wise, quite the same.
Personally, I see no difference between the right of having sex between family members, or gays/lesbians as any different. If they love each others, and want to fuck, nobody should be allowed to forbid them, as long as both are adults and consensual.
The only real issue, is the increased risk of pregnancy/birth/genetic issues, but nowadays, those are things that can be screened for, or even bypassed with planned parenthood.
But I guess that's another step forward in tolerance and acceptance society has to make... People are not allowed to judge or anything for some relations, but specific relations like incest, are still taboo and so on. Can't win on everything I guess
This is the most accurate thing I've found:
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You've got to select countries to get the details, in some countries, it's illegal, but there are no penalties for doing it, which in effect, makes it legal. Most of the incest laws, dates from so long ago, some may not even be applicable nowadays, but very few countries have been digging into the subject properly, because it's an uncomfortable subject I guess, with potential massive drawbacks during election times.