hyphenated last names

My in laws are sexist! Since my son was born, my father in law has repeatedly reminded me that he and my mother in law are the REAL grandparents since they share a last name with my son. He has the nerve to say this in front of my parents every time they meet. My husband keeps telling him to stop but my father in law wont listen. He still says it to everyone he knows. This has completely turned me off from wanting our kids to share his last name. My husband tells me all the time that he doesnt mind if all our kids have hyphenated last names  and while I want to rub it in my father in law's face, I also think both our last names combined sound really odd. What should I do????