whether I was talking about my cousin-sister or cousin-brother.
I thought that the sibling modifier was just to indicate to people the cousin's gender. Most languages in India have specific words for specific relationships. I studied Tamil and my mind swirled during one session where my teacher was telling me "ok, your husband's aunt on his father's side is called X. your husband's uncle on the other side is called X. No simple Uncle Steve and Aunt Faye here, but still no ambiguity as to how exactly that person is related to you. My daughter calls her father's father just that...in malayalam it is achachan - achan is father and they contract it to achachan.
So I asked my husband one day why people used the term "cousin- brother" or "cousin-sister." He explained that the sibling modifier is not just an indication of gender, but of the closeness that people feel with that relationship. In western families, the core or nuclear unit is all-important and all others are just secondary. In India, the core is important but each person connected to any given family is promoted a rung. For instance, cousins become brothers and
sisters, second cousins become first cousins, aunts and uncles are secondary parents (my husband calls his mom's younger sister "little mommy,' and his dad's younger brother "little dad", and any and every other person who is older than you is either called "older brother" or "uncle" or "elder sister" or "auntie," depending on the age difference.
When you are in India, you will hear so many people calling someone "Bhai" or "Bhaiya" (Hindi), "Ana" or "Aka" (Tamil).... to entreat the Rickwalla (Autorickshaw driver) not to cheat you, you might say "Meter Down, Bhai" as you get into the Auto.