Where did the phrase family jewels originate?

Answer 1

The phrase family jewels is a Victorian era euphemism for testicles, or more generally for the male's ability to procreate.

In the late Victorian period it was vulgar and offensive even to refer to the leg of a table, let alone to the leg of a person. The word "limb" was used for both leg and arm to avoid such unsuitable language. In this environment something more delicate was needed to refer to war wounds and other injuries that made a man unable to procreate, or perhaps uninterested in sex.

Because family wealth was often held as jewels, and their loss could ruin a family, the term was a favored choice in literature to describe the loss of a man's ability to create or continue a family line. ("He lost the family jewels.")