<human>: Can you condense the text into three sentences or less?

Background. My wife and I have an OB-GYN who happens to be Asian. We had an appointment for a fancy ultrasound thing last week at a different location. After the ultrasound, the doctor walks in, also an Asian and a female, and I began to say "Oh, hi Dr. ____," because I thought it was our OB-GYN, but I stopped myself just in time."  My wife swore that this made me racist for not being able to tell Asian women apart.

Fast forward to today. I'm back with our OB-GYN and she mentions in an off hand remark that the doctor we had at the hospital the previous week was her sister, which means they REALLY DO LOOK ALIKE! I'M SO HAPPY I'M NOT RACIST!
<bot>: I thought an Asian #2 was Asian #1, but she was actually Asian #1's sister so I'm not racist.