Sister Twister

(My half sister — same father, different mothers — is a freshman and I’m a senior at the same high school. Our last classes of the day are right down the hall from each other, so she sometimes pops in near the bell to tell me if she needs a ride home or not.)

Sister: “Hi, [Teacher], sorry to bother you. [My Name], Mom’s here so I’m not going to Dad’s today.”

Me: “Okay, see you tomorrow.”

Teacher: *bewildered* “If you drive, why would your mom even come here to pick her up? You’re going to the same place anyways.”

Me: “Oh, no, she lives with her mother. She usually has to go to our dad’s house after school because her mom works late.”

Teacher: *confused* “So you don’t live with your mother?”

Me: “…nooooo? I live with my father. [Sister] and I don’t have the same mother. Her mom is my ex-stepmother.”

Teacher: “Then how are you sisters?!”

Me: “We have the same father… She’s my half-sister.”

Teacher: “But… I just don’t understand. How is she your sister?! You don’t live together!”

Me: “She can’t be my sister if we don’t live together?”

Teacher: *exasperated* “YES!”

(Cue collective classroom-facepalm. One of my classmates is the teacher’s daughter. She head-desked pretty hard.)