My brother in law keeps asking me how his sister performs in bed

I’ve been going out with my girlfriend for three years. She’s Asian and originally from Singapore. About six weeks ago, I met my girlfriend’s family for the first time and, while I was alone with her brother he started to ask me some very strange questions about my sex life. He asked me about 20 questions on the subject of what Asian women are like in bed.

I’m Irish and, considering the only Asian woman he knows that I’ve slept with is his sister, these questions completely freaked me out. I honestly don’t know what to think. I would never talk about sex with my sister’s boyfriend, let alone ask specifics about his own sex life or any question that implied I was trying to find out what my sister was like in bed. It’s very, very strange to me.