Some sperm banks believe their counseling methods are adequate, although one deposit to a sperm bank can be broken down into eight to 20 vials. If a donor makes dozens of deposits, the numbers of potential offspring are staggering, and tracking successful births is not required.
In addition, only about 40 percent of mothers who give birth to sperm-donor babies actually report it to the bank.
After years of searching, Ryan Kramer finally discovered his donor father and developed a good, if slightly distant relationship, bonding over similarities such as an interest in mechanical engineering.
So far, he has established contact with six half-siblings, but said there could be closer to 20 or 30 potential siblings out there.
Two of Kramer's newfound sisters are Kristina and Natalie Pavone, who connected with Kramer on the Donor Sibling Registry. Despite fears at first that they would have nothing in common with a rocket scientist, they learned he was "an awesome guy," and that they were more similar than they had expected.
"There are parts of our personalities that are very similar," Kramer said.
Since meeting last year, the three siblings visit for holidays and big events, and they can't wait to discover more additions to their very modern family.
"The more, the merrier," he said. "Meeting my half sisters has been such a treat."