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Gamete donation is one of the greatest achievements of reproductive medicine, a practice that for decades has allowed thousands of people to build families they otherwise would not have been able to have. Historically, this system has stood on an iron pillar: the absolute anonymity of the donor. However, the proliferation of DNA testing low-cost commercial is literally dismantling this implicit pact. Today, with a few tens of euros and a saliva sample, genetic databases allow you to trace relatives around the worldraising enormous legal, ethical and health questions.
The numbers of a global (and Italian) phenomenon
The practice is much more widespread than you think. In the United Statesdespite the absence of a mandatory federal register, it is estimated that they are born every year between 30,000 and 60,000 children thanks to sperm donation.
In Italy, where gamete donation was banned until the Constitutional Court ruled that it was unconstitutional in 2014, the numbers are rising rapidly. According to the PMA National Register of the Istituto Superiore di Sanità, in 2023 more were carried out 16,400 cycles with gamete donationequal to 14.6% of all procedures in our country. This means today one in seven children born with assisted fertilization in Italy was born from a donation. There is an important technical detail: since voluntary donation is scarce in our country, the vast majority of gametes are imported from foreign banks (mainly Danish and Spanish). Many children born in Italy therefore have a biological parent who resides elsewhere in Europe.
How genetic testing circumvents the law
For decades the system has guaranteed anonymity: the parents did not know who the donor was and vice versa. This protected privacy and eliminated the risk of future legal or financial claims. In Italy, the law still guarantees that the newborn can only access general medical or physical informationbut not to identity.
Everything changed when companies like 23andMe And AncestryDNA they launched i DNA testing direct-to-consumer. Today these databases contain tens of millions of profiles. The algorithmic operation is ruthless in its precision: the system sequences the DNA and searches for matches. If you share the 50% of the genome with a user, is it a parent or a child, the 25% indicates a grandfather or half-brother, the 12% a cousin.
The real “bug” of the anonymity system is that The donor does not need to have taken the test himself. It is enough that a distant nephew or cousin did it: through genealogy and triangulations, those born from donation are able to trace theidentity of the donor. A 2020 survey conducted by the organization We Are Donor Conceived found that the 78% of those interviewed (a very active sample in research) identified their donor through these tests. The technology, operating on international databases, simply bypassed national jurisdictions.
The phenomenon of serial donors and the explosion of half-siblings
By cross-referencing genetic data, many people are discovering unexpected half-sibling networks, bringing to light the operational limits of some sperm banks and the legislative flaws.
The best-known case (recently also told in a Netflix docuseries) is that of the Dutchman Jonathan Meijer. By bypassing the legal limit in the Netherlands (set at 25 births per donor) and targeting dozens of international clinics and online marketplaces, it is estimated that it has generated between 500 and 600 children around the world, with unofficial estimates that go much further. In America, the activist Jamie Spiers discovered through DNA that he had at least 37 half-siblings, unmasking a sperm bank that had promised a maximum limit of six families for that specific donor, which had actually produced around 1,700 vials.
The two scientific risks: genetics and inbreeding
The figure of the serial donor not only raises complex ethical dilemmas, but brings with it concrete and measurable health risksstarting with transmission of silent genetic diseases. Emblematic in this sense is a case documented by a 2025 investigation: an anonymous donor, who became the biological father of at least 197 children in 14 European countriesturned out to be a carrier of one rare genetic variant associated with a serious oncological risk. The real problem is that, within a strictly anonymous system, tracking down and subsequently warning hundreds of individuals around the world of a similar health threat becomes a logistically almost impossible undertaking.
Added to this is a second danger, namely the statistical risk of inbreeding. If hundreds of children of the same donor are born and grow up in the same geographical macro-area totally ignoring theirs kinship bondthe probability that they meet by chance and decide to have children together increases dramatically. The union between half-siblings, who share well the 25% of DNAin fact triggers a high risk of activating recessive genetic pathologies. And it is exactly for this reason of a purely statistical and genetic nature, and certainly not for moral questions, that the Law 40 Italian has set an insurmountable maximum ceiling of 10 births for each single donor.
Psychology and legislation: the problem is the secret
The most recent scientific literature (such as a 2024 review on the British Journal of Obstetrics and Gynaecology) reassures on one point: people born from donation have levels of well-being and self-esteem equivalent to or above average. A 2025 study, published in Human Reproduction and based on a survey of 422 people born through donation in eight countries, found that the way in which it is discovered makes a lot of difference: those who found out from their family, intentionally and early, report significantly higher levels of satisfaction than those who discovered it by chance (from a DNA test, from a document, from a relative). Identity problems do not arise from the donation itself, but from the secret.
Today the legal debate is open. On the one hand there is the the child’s right to know his or her medical history and its own history; on the other there is the the donor’s right to have the anonymity agreement signed decades ago respected. While countries such as the United Kingdom, Sweden, Austria and the Netherlands have already abolished anonymity by law (also demonstrating that the number of donors is not collapsing, but is only becoming more aware), in Italy the hypothesis of a “double track” is being discussed to allow the donor to choose whether to make himself identifiable. In the meantime, however, millions of people around the world will continue to open a 99 euro kit, discovering that they are part of a gigantic global family tree that the law had not foreseen.
