My older brother served in the military for twelve years, and last year he was discharged and returned home. The first thing he did was take the whole family for a full medical check-up.

When they drew blood, he joked that as an O-type blood person, mosquitoes are attracted to him, and he should ask the doctor for more bottles of cooling oil. My dad sat nearby in a wheelchair, silent. My mom stood behind the wheelchair, her hand on my dad’s shoulder, also silent.
On the day the report came out, my brother held three sheets of paper and examined them all afternoon. He’s O-type, my mom is O-type, and my dad is AB-type. He lined up the three sheets, showed them to me, and said, “Look, I’m a foundling.”
I said, “You’re forty years old and only now thinking to ask about this?”
He didn’t speak, put the sheets away, and stuffed them into his jacket pocket. That pocket, he’s been in the army for twelve years, stuffed training uniforms, physical training clothes, but he’s never put a lab report in it.
The next day, he went to my parents’ house. I wasn’t there; later, my mom told me over the phone. She recounted the whole process, still muttering about what to eat for dinner while changing shoes at the door. When the door closed, my dad sat in that old wheelchair in the living room, with his back to the door, the TV on, volume very loud. My brother placed the lab report on the coffee table, my dad glanced at it, then turned off the TV.
The living room was quiet for a while. My dad said, “You know now.”
My brother said, “Mm.”
My dad said, “Your biological father isn’t me.”
My brother said, “Mm.”
My dad said, “Your biological father is the soldier I led.”
My brother said, “Mm.”
Then my dad said again, “The year your biological father sacrificed, you had just turned a month old. Before I married your mom, I promised him I’d raise you as my own. You served in the army for twelve years, and I never dared tell you.”
My brother sat on the sofa, flipping the lab report over and over again. He flipped it several times. Finally, it was my dad who broke the silence.
He said, “That AB blood type of yours is the first lesson I gave you — teaching you your blood type so that if you ever get hurt, no one will transfuse you the wrong blood.”
My brother asked, “Then what’s your blood type?”
My dad said, “I’m also AB.”
My brother stood up, walked to the wheelchair, squatted down, and placed his hand on my dad’s knee. He called out, “Dad.”
My dad responded.
He called again, and my dad answered again.
He called many times, and my dad didn’t get annoyed.
Later, my brother put away that lab report, placing it in the same drawer as his twelve years of military medals.
Inside the drawer, at the very back, was another piece of paper — the introduction letter from the army on the day he was discharged. The three sheets of paper stacked together, and he told me, “Only one of these shows his real blood type. The other two: one tells where he came from, and the other tells where he’s going.”