Q&A: Parentheticals and Subject-Verb Agreement

What is the grammatical correctness for a sentence such as:

George Smith (and Tom Johanssen, of course) are making a strong contribution to the operations.

OR

George Smith (and Tom Johanssen, of course) is making a strong contribution to the operations.

The question really is: Is the information in brackets included in the grammar of the rest of the sentence or is it ignored?

George Smith (and Tom Johanssen, of course) is making a strong contribution to the operations.

The second version is the correct one: George Smith (and Tom Johanssen, of course) is making a strong contribution to the operations. As The Chicago Manual of Style points out, any matter set off with commas, dashes, or parentheses does not affect the rest of the sentence.

• Sarah, and of course her clones, has issues with authority.
• Cyril—and Gussie too—is excited about starting school in the fall.

If the correct version sounds awkward, try rearranging the sentence.

• Sarah and her clones have issues with authority.
• Cyril and Gussie are excited about starting school in the fall.

After all, correctness isn’t much good without clarity.

Cyril and Gussie are excited about starting school in the fall.

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