I found him!
Nellie's Baby - A podcast by RNZ

Sarah and Kirsty call in the big guns: DNA. A strong match comes up: a woman who shares 28% of Sarah's DNA. Is it Nellie's first child? Eventually, Fran, the genealogist, suggests the match could be an aunt, and Sarah works up the courage to send a message to this mystery relative.To see more images and details about the series, vist the website here."To know that I have two people who did really want me - if he's mentally disabled and she was, they probably wanted me but they just couldn't - for the first time I feel like I belong properly." - SarahSarah and Kirsty call in the big guns: DNA. Working with a genealogist, they dig through ancestry records to try to find Sarah's relatives.A strong match comes up: a woman who shares 28% of Sarah's DNA. Is it Nellie's first child? But the woman's profile is private and all of Sarah's insecurities surface - do her family want nothing to do with her?Eventually, Fran, the genealogist, suggests the match could be an aunt, and Sarah works up the courage to send a message to this mystery relative.Go to this episode on rnz.co.nz for more details