A little less than 100 years ago, officials around Japan initiated a campaign to address what the government considered to be a grave threat — flies.

Yes, flies. Until then, flies had been considered to be rather harmless. Somewhat annoying, yes, but certainly not a threat of any type. However, a growing chorus of public officials began to see the insects as spreaders of disease, so laws were amended and campaigns were organized.

In Tokyo, the municipal government sponsored an annual “Swat the Fly Day” and offered money and coupons in exchange for dead flies. A philanthropist named Seiko Goto offered a bounty of one sen (¥0.01) for every fly produced. People around Japan actually competed to record the most kills, and during each summer of those worrisome years, over 100 million dead flies were reportedly collected throughout Tokyo.

A few decades later during the run-up to the 1964 Tokyo Olympics, Japan’s passion for sanitation continued as the government mobilized 1.6 million volunteers to clean the streets of Tokyo. But this campaign extended beyond the tidiness of the capital’s roads and alleyways to the perceived purity of the self, namely the celibacy of Japanese women.

The Tokyo Metropolitan Welfare Office established a Women’s Bureau headed by Tsuya Nakano, who described his agency’s efforts as follows: “We were worried because we saw cases in which young ladies of good background accompanied (foreign men), suspecting nothing, to bars or even their hotel rooms. We warned them that they should not cheerfully follow foreign — especially white — men.” An educational film was produced, 75,000 copies of a pamphlet were published, lectures for regional leaders were organized, and officials even stopped by schools to make personal appeals. Popular magazines fretted over the corrupting influence of foreign male sexual desire and emphasized the importance of saying “no” clearly.

Today, flies are of little or no annoyance to most people in Japan, and the government’s efforts in that regard might be considered a noteworthy achievement. However, an impartial observer walking the streets of modern-day Tokyo might consider the nation’s efforts to stymie intercourse between Japanese and foreigners to have been far less successful.

Since 1989, international marriages within Japan have numbered more than 20,000 per year, and the effect is markedly visible. Japan’s representative at the Miss World 2016 competition was born of a Bengali father. The father of television personality Rola is from Bangladesh. In the sports world, the dads of Olympic champion judoka Mashu Baker and sprinter Asuka Cambridge are American and Jamaican, respectively. And in politics, Renho, the head of the Democratic Party, is the daughter of a Taiwanese father. Encountering Japanese of mixed ethnicity is no longer uncommon. We do it every day.

But how many do we have? How many people residing inside Japan have some ethnically mixed background?

A few months ago, I was presented with this conundrum. I talked it over with a number of bright acquaintances, and most saw the task of coming up with a total as unachievable. Many naturally assumed that we would need to start from some date hundreds if not thousands of years ago, when we would presume that Japan was a nation of one ethnicity. And notwithstanding that false assumption, we don’t have hard data from thousands of years ago. In fact, we don’t have a whole lot of data from 100 years ago.

However, realizing that our DNA is slowly diluted over generations — e.g., we share only an average of 12.5 percent of our great grandparents’ DNA, and only about 3 percent of the DNA from their grandparents — I pondered what we would discover if we used the hard data that we do have.

So I began in 1965.

In 1965, we know that Japan had a population of around 100 million, about 0.7 percent of whom were non-Japanese. We also have the numbers for foreign nationals naturalizing from around that time. But most importantly, in 1965 and every year afterward we know exactly how many foreign citizens marry with Japanese inside Japan. We can thus correlate those marriages with births in subsequent years to give us a fairly accurate estimate of the number of children born inside Japan to a parent who did not originate from the country.

For the sake of simplicity, I’ll call this parent a “foreign parent.” At the end of this first generation, in 1989, we can state with relative certainty that at least 1.22 percent of the nation’s residents had at least one foreign parent.

Over the next generation (1990-2014), the fertility rate falls, but the number of non-Japanese grows at a yearly average of 3.18 percent and the number of foreign nationals marrying Japanese rises until it peaks at nearly 45,000 in 2006. By the end of this generation, 3.24 percent of the nation has been born having at least one foreign parent. Moreover, many in that first generation (1965-1989) of kids with one foreign parent would have produced their own children, meaning that 3.59 percent of the nation would now have one foreign parent or grandparent.

And what about the third generation (2015-2039)? Using the government’s own population projections for those years and making a few likely assumptions, we should expect around 7.64 percent of Japan to have at least one foreign parent by 2039, almost 9.21 percent to have one foreign parent or grandparent, and about 9.66 percent to have one foreign parent, grandparent, or great grandparent.

This projection assumes that during this third generation: 1) the foreign population continues to grow at 3.18 percent; 2) the fertility rate stays steady at 1.46; 3) the number of Japanese marrying foreign citizens matches the average for the second generation; 4) the lifetime unmarried rate matches the government’s projection of 23.6 percent; and 5) the number of naturalized citizens matches the average for the previous 10 years and dies off 50 years after naturalizing — all fairly conservative assumptions.

We can also use this third-generation data to give us a rough idea of where we actually are today — i.e., what the numbers would show if we had all the needed data to begin our first generation from 1940 and conclude our third in 2014.

A few years back, I noticed that a young Japanese colleague of mine from a city along the Sea of Japan seemed to resemble a few ethnically mixed children that I had encountered during my decades in Japan. I inquired about his background, specifically wondering whether a foreigner might have been part of his family two or three generations back. He did not have any knowledge of his bloodline being anything other than Japanese, but he curiously mentioned that his grandmother happened to have blue eyes.

Seeing the data above, naturally blue-eyed Japanese grandmothers might become slightly more common in the days ahead.

The author can be reached at mshassett@gol.com. Have you got something to say about the methodology or results? Your comments: community@japantimes.co.jp

Facing the fact gaps

These findings factor in the lifetime unmarried rate and the effects of death and divorce. However, the numbers also come with a number of caveats, each of which would have a small impact.

For example, a lack of data forces us to classify ethnically Japanese foreign nationals and naturalized citizens — e.g., children born overseas to Japanese immigrants — as foreign. Also, children born out of wedlock, accounting for 1-2 percent of all births in Japan since 1965, would vary in assigned nationality based on the gender of the foreign parent.

Those caveats, along with a handful of others, would not be expected to sway the numbers too much in one particular direction. But a few could have a significant impact.

For one, Ryukyuans are classified as Japanese. In addition, a lack of data forces us to classify the entire indigenous Ainu population as Japanese too. A 2013 government survey reported the Ainu population to be 16,786 in Hokkaido, and a 2011 survey reported the population to be 210 for the rest of Japan, but some observers assert that these numbers should be much higher.

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