Your words ring very true. In my culture, our Ancestral tongue was Yiddish. By the generation of my grandparents, it was used only to keep the children from understanding. By my Mother's generation she knows only some of the common expressions. I know even fewer of the expressions.

Parents, please expose your children to other languages and to your own native tongue. They will never be more open to learning languages than when they are really young and it will enrich their lives forever.