In a scenario straight from science-fiction, experts are increasingly concerned about lax rules for sperm donors in the US and Canada where some men have anonymously fathered dozens of children.
Unlike countries such as France and Britain, there are no laws in either Canada or the United States officially limiting the number of children who can be born from a single donor, the Canadian health ministry said.
An international norm places the ceiling at 20 pregnancies from the same donor, most sperm banks set their own regulations.
But the rules are not always respected. Some families try to create a "designer baby" by carefully choosing the donor from a catalog, drawn by his particular genes or characteristics, such as eye color or IQ level.
The practice has meant some of these star donors have now left a huge and at times overwhelming legacy, and the issue has stirred recent debate in Canada and US, spawning a number of films and documentaries.
Starbuck, a popular Canadian comedy released this year, told the story of a perpetual bachelor who accidentally fathers 533 children by selling his semen for quick and easy cash.
In a reality series called Sperm Donor presents one donor, Ben Seisler, 33, who tells of his surprise on going onto the registry and of learning that "to date I know of around 70 kids."