Stabbing the Privates

Neil Elliot, in the book mentioned in the previous post, says that “The conspirators who assassinated Caligula included an officer he had sexually humiliated, who stabbed the emperor repeatedly in the genitals.” I recall that Plutarch records something similar about Brutus’s strike against Julius Caesar.

Does this suggest that striking at a man’s privates was common to assassination, a way of symbolizing that a man’s power is being cut off? Or does this suggest some sexual relationship between Julius and Brutus, something of which Shakespeare tells us nothing?