Strange but ultimately positive genetic discovery reveals up to 1,000 relatives linked to prolific sperm donor

Jack Nunn was 21, his girlfriend a year younger, when she died suddenly while the pair were in England.

Jack Nunn began working with health charities, and wondering how the public could be part of questions around research, policy and funding priorities.

This was long before regulations started to catch up with sperm donations. But DNA matching through ancestry websites means more people are finding out not only that their social parents or grandparents are not their biological relatives, but that they have far more genetic relatives than they could ever have imagined.

Wikipedia, he points out, lists Genghis Khan as the man who has fathered the most children in the history of the world. Coming in second is Wiesner.

When the family gave her the DNA test for her 65th birthday, she was surprised to find she was about 50% Ashkenazi Jewish. She assumed that came from her Greek grandfather, and uploaded the results to GEDmatch, a genealogical site similar to Ancestry.com.

She found more half-siblings, and found out about Wiesner and Barton.

Now she talks and meets regularly with more than 50 people who share Wiesner as a biological father.

But there has been an increase in informal sperm donation, using social media sites such as Facebook. Recipients, mostly single women and same-sex couples, are forgoing the regulated clinical industry in favour of finding a donor online.

For Barbara Nunn, the most important issue is the right to know.

In his PhD, Jack Nunn looked at several communities. One with a rare disease, another multigenerational study, another with a remote Aboriginal community.

And he looked at his own donor family.

He included his half-aunts and uncles in co-designing that part of his published PhD. Now they are exploring the possibility of setting up a family biobank, so they can all be involved in shaping future research on this intriguing cohort.

Nunn set up a feedback loop between his personal life and his professional work, and worked on standardised ways of building transparency into research, of ensuring democratic access and informed consent about how DNA data is used and shared.

Nunn says everyone reacts differently to finding out their genetic history, but he personally looked forward to a planned meeting with his relatives in London.

Nunn says those interactions flipped his ideas about the age-old debate about nature versus nurture, about what it meant to have a community with shared ancestry, and about how to involve that community in his work.