Most children learn how to swear before they even know the alphabet, according to a new book that examines bad language and its origins.

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In Holy Sh*t: A Brief History of Swearing, Mellissa Mohr argues that English-speakers actually use a curse word about once every 140 words, the Daily Mail reports.

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That makes foul language as popular as first person plural pronouns like "our," "us" and "we."

Among the book's findings:

• Cursing usually "kicks off" when a child is 3 or 4.

• About 0.7% of all English words spoken on a given day are swear words.

• The middle class curses less than the wealthy — a Victorian-age habit that "indicates that you are a proper, good person and this is a sign of your morality and awareness of social rules," says Mohr.

• "Aristocrats have a secure position in society, so they can say whatever they want — and may even make a show of doing so," Mohr adds.

• Cursing can be valuable, relieving us of pain (think hammer on finger) or helping us bond with others (like workers complaining about their managers).

• Cursing goes way back: Like us, Romans insulted people with curse words related to sexuality. The most basic of curse words — "sh*t" — dates back to Anglo-Saxons who spoke in Old English.

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