I saw this in a Facebook group: https://geneticliteracyproject.org/2019/01/16/im-a-geneticist-a-dna-test-uncovered-a-half-sister-and-sparked-painful-questions/. If you are not familiar with the term NPE, it’s generally called Non-Paternity Event or Non-Paternal Event although Not the Parent(s) Expected is a better term since it’s not always a case of Who’s the Daddy, but Who’s the Mommy, or Who Are the Parents.
A friend came across an unknown niece, but he should have expected it for the reason below. His brother paid for medical school by selling to the local sperm bank on a fairly regular basis. So far, she’s the only known DNA connection that my friend has come across as a result of the sperm bank donations. The interesting thing is his brother was promised anonymity back in the 1970-1980s which was blown out of the water by my friend testing.
A percentage of NPE folks are part of the “donor conceived” world. And we’re connecting and sorting ourselves out on Facebook: We Are Donor Conceived, DNA For The Donor Conceived (DNA Detectives), DNA NPE Friends. These online support groups are vital until and probably beyond when the psychotherapy community catches up with the new reality, as the media overflows with stories of insta-families.
When I do DNA presentations, I stress “expect surprises and it depends” because yo u may find full or half-siblings you didn’t know about. You may find one or both of your parents turn out to be somebody other than the people you called Mom and Dad.