So far as I know, my parents have never uttered a profanity or a vulgarity. So far as I know, neither have my children. Having never heard them use rough language I can only assume that they do not. You should also note that I am not delusional. Instead, these understandings represent the venerable tradition known as the Polite Fiction.
The polite fiction differs from its cousins the White Lie (“Do these pants make me look fat?” “Heavens, no!”) and Hypocrisy (“The bank has your best interests at heart!”). For, while the white lie protects someone and hypocrisy acts as a disguise, the polite fiction indicates respect. It seeks first and foremost to be polite, and is distinct, therefore, from Don’t-Ask-Don’t-Tell which facilitates denial.
Generally speaking, the polite fiction (“All teachers at our school admire one another and the principal”) is suspected or known by all parties to be a fiction, but the statement’s veracity is never pressed. It acts like the willing suspension of disbelief—allowing all to maintain the personae they have constructed for the purpose of social interaction.
There is a place in this world for the polite fiction, though the practice may seem a bit quaint—like handwritten letters on elegant stationery. It can also seem like too much effort when we’d rather just be ourselves and let other people deal. Still, politeness is never out of fashion, and sometimes we are happiest when we don’t reveal how well we know one another.