World's rarest sperm

Around the world, sperm donors fulfil a crucial role in reproductive medicine. These donors can be life-changing for individuals who find themselves unable to reproduce in more conventional ways. But beyond the widespread perception that sperm donation is a simple procedure and an easy way to make a quick buck, it is actually much more complex. In fact, applicants can be required to undergo rigorous background screenings and stringent health exams, and may need to donate regularly for a year or more. It’s a process that demands serious commitment and dedication.So who donates sperm, and what are these people like physically, mentally, and emotionally? It’s a diverse cross-section: the United Kingdom’s sperm banks not only store samples from U.K. men, but also donations imported from nations around the world such as the U.S. and Denmark. We used public, anonymised data available from six privately-managed sperm banks (also called “cryobanks”) to analyse how frequently various physical and other traits occur among donors. Read on to learn more about the people who help meet this critical need in assisted reproduction as well as the many factors influencing who is allowed to do so.

Even within the U.K., the practice of sperm donation hardly stops at the country’s borders: According to a U.K. report on sperm donation from 2012 to 2013, about a third of banked sperm in the nation is actually imported, typically from the United States or Denmark. For that reason, even U.K. sperm banks end up representing a far more global cross-section of donors.

We calculated which physical features were the most uncommon among donors. For instance, strawberry blonde hair was seen among only 0.41 percent of sperm donors – fewer than 1 in 200. While reddish shades such as strawberry blonde are similarly uncommon around the world, they are most prevalent in European populations. Conversely, black-coloured eyes were represented among fewer than 3 percent of donors. Note that black eye colour is actually a more extreme variation of brown eye colour, one of the most common colourations in the world – more than half of the world’s population has this eye colour. Additionally, medium-brown skin colour (identified by the donor agency) was the least common, comprising only about 1 percent of donors, as was adherence to Buddhism – another 1-in-100 trait. Similarly, only 0.4% of the UK population identifies themselves as Buddhist. Educational achievement is also recorded for many donors, and we found that science was the least represented area of education. The UK notably has a shortage of graduates in science, technology, engineering and medicine-related fields.

Next, we looked at which traits were most common among the donors examined.

Which traits are you most likely to find among men who’ve successfully donated sperm to cryobanks? Brown hair colour, also the most common in the world, held a strong majority at nearly 60 percent, and more than 43 percent of donors had brown eyes. The largest share of donors – more than 43 percent – had a fair or pale complexion (identified by the donor agency). While skin colour is not wholly analogous to race or ethnicity, 87% of U.K. residents are white British.

Christianity, at 38% (compared to 59% of Britons who identify themselves as Christians) was the most strongly represented faith group and was more than 35 times as common as Buddhism. And the most frequent field of educational achievement was business or accounting – 34 times more common than science.

We’ve seen which traits of successful donors are the most and least commonly represented, but how do other features stack up? Applicants for sperm donation may be expected to go through lengthy screenings that can ultimately remove all but perhaps one or two out of every 100 applicants, which may influence the overall composition of the donor pool.

Strawberry blonde may have been the least frequent hair colour, but the basic blonde colour was seen among nearly 15 percent of donors overall. Black hair was moderately common, seen in roughly 21 percent of donors, while red/auburn hair was very rare (fewer than 3 percent). The most common eye colour was brown, followed by blue (about 28 percent) and hazel (about 16 percent).

Body weight is a factor often taken into account when a man seeks to donate sperm, and many cryobanks may turn down an applicant whose weight is outside of the healthy range. U.K. sperm banks may specifically hold to such a guideline as well. A majority of the successful donors we researched, 56.54% had a healthy BMI, defined by the World Health Organization as a BMI of between above 18.49 and below 25. Only 30.38% of donors were overweight, and a still smaller 12.79% were obese. This was strikingly different from the distribution of BMIs seen among all U.K. men: less than a third of all men - 31.6% - are not overweight or obese, while more than 4 in 10 are overweight, and more than a quarter are obese.

While members of many religious faiths have debated the moral acceptability of donating sperm for use in artificial insemination, the donors in our study - who donated sperm in the United States - showed a mostly typical breakdown of faith identifications for the Western Hemisphere. More than 38 percent of the donors listed themselves as Christian (this number did not include the additional 19 percent who identified as Catholic or the nearly 2 percent who identified as Protestant). Atheists and agnostics made up the second-largest share: Thirty-two percent, or nearly a third. Less common faith groups included Judaism (fewer than 3 percent), Hinduism (2.4 percent), and Islam (roughly 1 percent).

Many cryobanks consider certain personal features to be particularly important when considering a potential donor, and not all of these features are objectively measured. Some sperm banks conduct one-on-one interviews with applicants to develop a more subjective sense of these men as individuals, evaluating aspects like friendliness, politeness, and overall demeanour. Cryobanks aren’t simply looking for quality genetic material – they’re looking for quality characters, too.

Descriptive information was provided for many of the donors we studied. The most frequently-mentioned trait was a good sense of humour, followed by a laid-back personality. Other features indicating a well-kept appearance were also mentioned, such as white teeth, a great figure and muscular build, and a defined chin.

As we’ve seen, sperm donors around the world undergo rigorous screening to ensure the most successful results for those who use their services. But whether or not donation is a part of your life, sexual and reproductive health certainly is, and that deserves just as much attention.

At ZAVA, we offer personalised services provided by experts in sexual health and family planning, including consultations and medications for contraception and STI tests and treatment. Following a consultation, all treatments, prescribed by a medical professional, are delivered discreetly to your home the next day. Visit zavamed.com to discover how you can take charge of your sexual health.

We collected public information of over 1,000 sperm donors from various donor websites to determine their most and least common characteristics. In some cases, eye colour, hair colour, complexion, and other information were grouped into larger categories. For example; various shades of hazel eye colour were grouped into a single “hazel” eye colour category.

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