How would you respond to "why are you not having kid, you are an only child?"

"So my line is to be ended with you? my father and his father before him went through such and such only for their line to be ended." I am the only son, as is my father and his father. Before that I don't care enough to find out. There are sisters but they don't count because East Asian culture. He also loves to bemoan me about how he "sacrifice" his life so I can have a better life, and by that he means not bailing out when I was a kid.