"My grandfather's name is Garam."
Translation:우리 할아버님의 성함은 가람이에요.
how come we don't use 께서 instead of 은? Thought that was the honorifics version?
Using 제 할아버님 would sound like you were saying you were the only person to have a grandfather. Native Korean speakers have a communal culture, whereas Westerners typically place greater importance on individuality.
The mentality is rooted in each language. Native English speakers' first thought is, "What is the thing?" Native Korean speakers think, "What is happening?" first.
Because of this, shared experiences use 우리.