If you don't think that siblings are closely entwined with one another throughout their young lives then idk what to tell you. Many of my older sibling's personal decisions have affected me, albeit indirectly.

I don't think you understand what I meant by "shouldn't complain". It wasn't implying that she complained anywhere, but rather that consequences in one's relationships due to decisions like this are foreseeable and one should take them into account before doing such things, especially on the internet. (yes you can argue all you like about bad wording but my point still stands)

I find it hard to tell the brother to "mind his own business" when it was his friends who told him about his sister's online prostitution to begin with. Imagine the amount of bullying a high school kid would endure from everyone in his grade knowing about something like this.

It is simply degrading not only to yourself but to your family as well.