Who is your "brother", "sister"?

Thursday, April. 28, 2016

 When I say "This is my brother", it is a blunder for you to ask me: "Is he your biological brother?" Truth is that in Standard English, your "brother" is your male sibling that you share the same blood with. i.e. From the same parents, same father or mother. In this part of the world, we call every male "brother"; say Church mates, classmates, friends, etc.
Same applies to "sister".

Let me treat "uncle " and "aunt" later.

 I understand that idea though, but we are talking English here. Is that clear?