My best friend had a baby at sixteen. She never told anyone who the father was, and I never asked. Years passed, and I grew close to her son, Thomas. One day while babysitting, I noticed a birthmark on his shoulder that looked exactly like the one that runs in my family. I tried to ignore it. It kept nagging. I took the spoon he had used and sent it for a DNA test. Part of me hoped I was wrong. A few days ago the results came in. I stared at the screen, completely stunned. It said Thomas was my half-brother.

I sat with the report for an hour before I called her. She did not deny it. She said my father had been the one. She had been sixteen, he had been married to my mother, and she had been too afraid to name him. She had watched me become close to Thomas and had decided the secret was safer than the truth. She asked me not to tell him until she could do it herself.

I did not answer right away. The birthmark had been the first clue, but the report made it plain. Thomas was not just a friend’s child I had grown to love. He was my father’s son, and I had spent years in the same room with him without knowing. My father had died three years earlier. There was no one left to ask.

I told her I would keep the report in a drawer until she was ready, and that Thomas deserved to hear it from her first. She said she would tell him that weekend. I put the phone down and looked at the birthmark in the old family photo on my wall. It was the same shape. The test had only confirmed what the mark had already said.