Q. When referring to Orville and Wilbur Wright as a unit, should the word “brothers” be capitalized—Wright brothers vs. Wright Brothers?
A. According to CMOS 8.37, “A kinship name is usually lowercased unless it is used as part of a personal name or in place of a personal name.” One of the examples at 8.37 is “the Brontë sisters,” who, though none of them lived to see the age of modern aviation, provide a perfect analogy in terms of capitalization: Write “the Wright brothers.”