I have seen the question on when to capitalize mom and dad, but I am confused why the rule would not apply equally to Brother vs. brother and Sister vs. sister.
I.e., if the rule is to use capitals when speaking of a specific mom, as in "my Mom", then should the rule compel me to refer to siblings as "my Sister" and "my Brother"?
It looks perfectly acceptable to capitalize parents, but capitalizing siblings looks extremely odd.