Guess these were all the exceptions you could find.
USA has local state laws with up to 10 years of prison.
Funny you mention Germany, their incest laws are among the strictest of the world.
Also, i wouldn't consider places like Russia anywhere near the "most developed countries". Russia is currently #56 in the Human Development Index, after countries like Romania, Chile, Turkey and such.
I couldn't help but mention this, considering that almost all the BB developers (except for the version In Space) are from Russia.
As for the USA, there are too many laws for each State. That's why I'm not even considering them.
As for the exceptions I have listed, these are the most obvious examples. There are actually a few more of them.
If you look at information on all countries of the world, the Legal information label will very often appear.
You can also find countries with really harsh laws where same-sex relationships between relatives are allowed.
This suggests that the authorities of the countries are not afraid of the fact of sex between relatives, but of the genetic consequences due to the mistakes of lovers. Give people free rein and they will begin to breed the Habsburg and Tutankhamun dynasty.
Although, given the huge number of children with serious genetic abnormalities, I would not be surprised if some of them are victims of incest. However, that's
Another Story.