Incest between adults is not a crime in all jurisdictions. In France, the offense was abolished when Napoleon introduced his new penal code in 1810. Consensual adult incest is also not a crime in Belgium, the Netherlands, Portugal, Spain, Russia, China, Japan, South Korea, Turkey, Côte d’Ivoire, Brazil, Argentina, and several other Latin American countries.
This map should be of great help.
The report does not attempt to provide a definitive assessment of the ethics of consensual sexual relationships between siblings. Instead, it asks whether there is an adequate basis for the criminal law to prohibit such relationships. It points out that in no other situation are voluntary sexual relationships between people capable of self-determination prohibited.Singer notes that the report goes on to talk about Discredited Arguments #18, 19, and 20.
The taboo against incest runs deep, as the social psychologist Jonathan Haidt demonstrated when he told experimental subjects about Julie and Mark, adult siblings who take a holiday together and decide to have sex, just to see what it would be like. In the story, Julie is already on the Pill, but Mark uses a condom, just to be safe. They both enjoy the experience, but decide not to do it again. It remains a secret that brings them even closer.
Haidt then asked his subjects whether it was okay for Julie and Mark to have sex. Most said that it was not, but when Haidt asked them why, they offered reasons that were already excluded by the story – for example, the dangers of inbreeding, or the risk that their relationship would suffer.That's because they don't want to admit their reason is simply that they wouldn't personally want to do it. However, their personal disgust should not prevent other people from enjoying sex or loving as they mutually agree.
In the case of the incest taboo, our response has an obvious evolutionary explanation. But should we allow our judgment of what is a crime to be determined by feelings of repugnance that may have strengthened the evolutionary fitness of ancestors who lacked effective contraception?
Even discussing that question has proved controversial. In Poland, a comment presenting the views of the German Ethics Council was posted online by Jan Hartman, a philosophy professor at the Jagiellonian University in Krakow. The university authorities described Hartman’s statement as “undermining the dignity of the profession of a university teacher” and referred the matter to a disciplinary commission.
I would argue that it is immoral to use government resources to try to prevent consenting adults from loving each other how they wish, or to discriminate against them by denying them their fundamental right to marry. Germany, and many other countries, need to drop the discrimination against consanguinamory and embrace full marriage equality.