I think modesty is a culturally loaded concept, and the qualifier 'proper' adds a whole other dimension to this as a cultural issue.
Of course, every family defines that differently. What I should just have directly said is that we aren't nudists. (But we have known some). We do put on clothes when guests come to our house. There is some accepted standard of "modesty" in every place and in Hong Kong, as well as where I grew up, the standard was that you don't show your private parts (breasts and genitals for women & genitals for men) to other people outside of your immediate family and then that is further interpreted according to age and family custom as well as the other things I talked about in my other post. Every culture and place does have a certain standard of modesty (what is okay and what is embarrassing or uncomfortable) and of course, it goes without saying that every culture is different in their interpretation of this as well as there are subsets in every culture that further interpret those standards differently.