My family went through something similar a few years back. My parents are really into genealogy, and about a year before my grandpa passed, we got him to take an Ancestry test. Well, over a year later, my parents got a notification that someone on the site was most likely his daughter due to the percentage of DNA shared, and we were all over the moon! She was born over a year before my grandparents were married, and her mother moved away well before she was born, leading us to believe that my grandfather had no idea that he had another daughter. She was ecstatic to learn about her family, and both she and my dad share the same gap in their front teeth which I thought was really sweet. They just got to meet her last month, and she seems like the coolest aunt, so this is all to say that those DNA kits are pretty awesome, and because of it, we were able to find someone that were so happy to now have in our lives!