Society generally dictates what is OK or acceptable. I grew up where it was generally not 'normal' for kids to see a females breasts.

Thankfully society has now allowed woman to nurse in public places. It allows the Mom to nurture her child in a very natural way.

Are breasts sexy? Yes. But almost any part of my lover is sexy when we are in the mood.

But then again it is not my body that is being seen, so the comfort level must depend on her.