Trying to understand my mother's attitude toward s?

My cousin, who is 18, had it one her Facebook that she's "interested in women". My mom was upset and said it was a "tragedy". I mean, my mom doesn't have anything against uals. She had a roommate in university who was a and has had gay and friends. However, she doesn't believe that ity really exists. She isn't religious either. I am straight but I don't intend to ever get married or have children. I'm ually attracted to men but not interested in relationships. My mom sort of knows that I won't ever marry and that I don't want kids (in my family people don't have children unless they're married). I'm wondering -- what's the difference? daughter or Never-married daughter. No grandkids or in-laws either way.