What is the origin of the idiom "Benjamin of the family" and when to use it?

The phrase "Benjamin of the family" is derived from the biblical story of Benjamin, who was the youngest son of Jacob and Rachel in the Old Testament. In the story, Benjamin held a special place in his father's heart as the youngest child. It is used o describe the youngest sibling in a family, emphasizing their status as the last born. It conveys the idea that the youngest child is often seen as loved or favored by their parents and may benefit from the attention or special treatment that comes with being the 'baby' of the family.