The limits—voluntary, self-imposed—come up against an even more basic problem: No one knows exactly how many donor-conceived children are even born in the U.S. every year. A woman might buy sperm from a bank, get inseminated at her fertility clinic, and then have her baby with her ob-gyn. The sperm bank relies on customers to report back, but it has no way of compelling them to do so. Anecdotally, at least, parents and kids curious about their donors have found these records fairly incomplete.

“You really can’t do anything until you have accurate records,” says Wendy Kramer, the founder of the Donor Sibling Registry, a website that connects donors and donor-conceived people. In 2017, Kramer submitted a citizen petition asking the Food and Drug Administration to regulate sperm donation, including the number of offspring per donor. The agency declined, saying those matters were outside its scope.

Given the lack of official records, it’s unclear exactly how Matteo knows that he has 114 biological children. He is only 25, so any biological children would be too young to take DNA tests on their own. He does not appear to be on the Donor Sibling Registry either, according to Kramer. ABC, which airs The Bachelorette, declined to clarify when asked for comment. And yet, given what is known about the sperm-donation industry, 114 is certainly within the realm of possibility.

Cynthia Daily used a sperm donor to conceive her son in the 2000s, and she now runs a private Facebook group for his half siblings and their families. The total number of children from that donor is, so far, 189. The group has been fairly healthy, but Daily pointed to examples of other donors who have passed on genetic conditions. “What if you have a donor who’s passing on something they don’t test for? Or it’s a later-in-life potential issue?” Daily asks. “We don’t have any clue what happened in his later life. All we know is what went on when he was a freshman, sophomore, junior in college.” Sperm banks could at least mitigate some of the risk by limiting offspring from a single donor.

It’s also just hard to imagine what it means to be one of more than 100 children. What are the psychological effects, Kramer asks, “for a child to be part of a herd of children?” Or for a donor, who might have donated for spending money in college, to find out he has 100 offspring? One donor has taken to keeping track in an Excel spreadsheet. “It’s kind of overwhelming to think about,” says Naomi Cahn, a law professor at George Washington University and the author of The New Kinship: Constructing Donor-Conceived Families. But, she adds, finding so many half siblings could also be welcome for some people.

For Daily and her now-teenage son, who grew up as an only child, meeting dozens of half siblings all over the country has indeed been welcome in many ways. They have gone on annual vacations with donor siblings. When he travels for ice-hockey games, they meet up with whoever is nearby for lunch. (They have not been in touch with the donor, and Daily says her son is not particularly interested.) The number of siblings in Daily’s case is unusual, but such stories are not. As donor-conceived people have found their donors and their siblings, they have created new types of family bonds.