Is it inappropriate to wear cheeky bikini bottoms around some people?

I live near the beach so I'm in a bikini pretty often, especially in the summer. Cheeky style bottoms are very popular here and that's what I always wear to the beach. My roommate is upset with me though because I wore my normal swimsuit to the beach with her and her family when they came to visit. She claims I was inappropriately dressed and that half my butt was showing (false) all day with her family around.
Is it inappropriate to wear cheeky bikini bottoms around some people?
Post Opinion