The Twisted Ladder

Shereena, an only child, has just lost her mother. She goes back to work shortly afterwards to distract herself from her grief - at a genetics testing company. When she started this job, she set up an alert to notify her if she had a DNA match with anyone who came up in the system. A match comes up, but the person doesn't want to be contacted. What lengths will Shereena go to in order to find her last living relative?