Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Tear Jerker: Maury
One of the saddest examples from Maury came when a fifteen-year-old teen mom was murdered, and an eighteen-year-old man said he thought he was the father, and even wanted to be. He was brought on with the deceased teen's mother and sisters. It turns out he was not the father. On top of that, the only other candidate to be the baby's father was also dead.
On one episode, a man named Dwayne came for two DNA tests, to find out if his daughter Savannah was his, and to find out if his father Randy, who raised him from birth, was his biological father. Turns out, neither are related to him.
Another paternity test had a woman who was trying to find out if her son, who was killed in a traffic accident a few months before her appearance, was the father of a baby boy. He was. The joy the mother had for having a grandchild was definitely worthy of tears. A little while later, she came back to the show again to find out if her son had also fathered a school-aged boy by another woman. Likewise with the infant, he was also the father of the other little boy.
Another show involved missing and murdered persons, including a mother whose 22-year-old daughter was murdered in 1996 and has been actively helping in finding her daughter's killer ever since. At one point, one of Maury's production team members portrayed the daughter in a dramatization of her story and the mother even said the resemblance between the woman and her daughter was so strong, she had to look away when the piece was playing.