Strunk and White
Still my Bible
They. A common inaccuracy is the use of the plural pronoun when the antecedent is a distributive expression such as each, each one, everybody, every one, many a man, which, though implying more than one person, requires the pronoun to be in the singular. Similar to this, but with even less justification, is the use of the plural pronoun with the antecedent anybody, any one, somebody, some one, the intention being either to avoid the awkward “he or she,” or to avoid committing oneself to either. Some bashful speakers even say, “A friend of mine told me that they, etc.”
Use he with all the above words, unless the antecedent is or must be feminine.
Do you think all of these sentences below are incorrect and poor usage; and how would you state them otherwise in everyday language?
“Somebody left their umbrella in the office. Could you please let them know where they can get it?”
“My personal rule is to never trust anyone who says that they had a good time in high school.”
“The patient should be told at the outset how much they will be required to pay.”
“But a journalist should not be forced to reveal their sources.”
Rule of thumb our grade school teacher taught us.
If the answer is “her” or “him”, use whom or them.
IOW, the words all end in “m”
Example:
Q. To whom should I send it?
A. Send it to them.