Some American exports make their way around the world for their novelty or technical prowess (or through aggressive marketing). But America’s rise as a top exporter of sperm has less to do with the quality of the product than it does with the process, according to a new story by Brooke Jarvis for The Verge.

For the most part, over American history, the flow of people—or more specifically, genetic material—has predominately been into the country. But while America is still largely a destination for families on the move, according to Jarvis, “by some estimates, the United States is the world’s largest exporter of sperm, sending vials to dozens of countries every year.” From one Seattle sperm bank, she writes, “some 60 percent ends up outside the United States.”

“perm has become a vigorous (ahem), multi-million dollar global industry. The sperm trade is growing ever larger and ever more international, with more and more kids being born via unknown fathers on distant continents.”

“Why is US sperm so popular?” asks Jarvis:

It’s not about the superior fitness of American males, exactly. One reason is that the US’s immigration history means lots of ethnic diversity. For some would-be mothers from other parts of the world, this can give US product a leg up over places like Denmark, another sperm exporting powerhouse. Another is all that tracking and testing: the U.S. has some of the world’s highest standards for disease testing and donor screening. The FDA defines sperm as human tissue, and regulates it much as it does the donation of organs. …But while medical testing requirements are comparatively strong, other US regulations are much looser than in some other nations — a fact that has been a boon to the US industry, but has also led to controversy. …Unlike many countries, the US allows men to donate anonymously and to be paid for doing so, leading to a comparatively larger donor pool; sperm donations in other countries plummeted following laws prohibiting anonymous donation or payment.

So where empires of old were forged through blood and steel (one in 200 men are reportedly the direct descendants of Ghengis Khan), America’s will grow through the mail.

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