In re: Aspects of Upbringing.

In the Indian context: If someone MUCH younger than you calls you by your first name without using 'Ji', 'Sir/Ma'am', 'Bhai/Didi', 'Uncle/Aunty' et al, do NOT get annoyed.

It makes him or her a smaller person & reflects his or her upbringing.

PS: I avoid using 'Bhai/Didi' & 'Uncle/Aunty'. I prefer using Ji & Sir/Ma'am.