John asks:

In a recent episode of Hand Shakers a character revealed that had romantic feelings for their biological sibling. This is nothing new with series like Oreimo , Boku wa Imōto ni Koi o Suru , and the classic Koi Kaze to name a few. Which got me to wonder about why incest is such a prevalent subject in anime and manga. Is this because incest was common practice in Japan's history or is it just trope similar to the beach trip to add another dimension to the story? And if incest was practiced what is its history in Japan and how accepted is the practice today in Japanese society?

Since Japanese media is so much more open about incest (and incest sexual fetishes) than the Western world, I think it's crossed all of our minds at one point or another: why does this topic come up so much? Does it have something to do with Japan's history or culture that we just don't get as Westerners?

The truth is, historically Japan has not had any real problem with incest -- in fact, clans would traditionally encourage relationships among cousins (or second cousins) to perpetuate family dynasties. If a father was widowed, he would often marry his daughter. Practices like this continued well into the 20th century, especially in very traditional rural families. Indeed, incestuous relationships were so common in olden days -- between siblings, cousins, aunts/nephews, uncles/nieces and the like, that genetics experts say this has introduced all sorts of problems into Japan's DNA.

By the postwar era, most people's attitudes towards incest had turned to complete disapproval, likely due to the introduction of genetic science (and probably a moral influence from the West). It's now common wisdom that Japan's bloodline is a mess due to all the in-breeding. A few Japanese friends and co-workers of mine were actually surprised to find out that Westerners have allergies too, since they thought that was one of the genetic problems introduced to Japan that way. But incest is not illegal there, and as piles and piles of Japanese media can attest to, its forbidden nature has turned it into a fetish.

In more recent times, there have been reports that counselors in Japan have seen a lot of mothers who have been having sexual relationships with their teenaged sons. The reports were that the mothers were lonely housewives whose husbands were essentially always at work, and rationalized the relationship by saying they were keeping them clear-headed and focused on their studies rather than girls. If the household is one in which everyone sleeps in the same room, the father is always gone, and it's just the lonely mother and the hormonal teenaged son there most nights... well, oedipal complexes are a thing.

This sort of thing is not talked about in Japan. Studies are difficult to come by, because many officials deny that something as shameful as incest ever occurs. There have been a handful of books on the subject (I got most of my information from this article from 1991), but how much or how little this taboo affects modern day Japan is simply not something that can easily be measured. But with centuries of incestuous history, it seems that simply acknowledging its fantasy potential will never be as shocking or taboo as it is in the Christianity-influenced West.

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