Did you ever hear of the American dating rule: "half-your-age-plus-seven?"

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The American "half-your-age-plus-seven" rule:
The "never date anyone under half your age plus seven" rule is a rule of thumb used by some in the American culture to judge whether the age difference in an intimate relationship is socially acceptable.The rule existed as early as 1951, when it appeared in the play The Moon is Blue by F. Hugh Herbert, and subsequently in the 1953 Otto Preminger film of the play.