A reader sent me this example of the use of brainchild:
According to Tesla’s brainchild, Elon Musk, demand for stationary storage batteries has skyrocketed to the point that an expansion of the gigafactory may have to be considered before it is even built.”
Opines the reader, “Either Nicola Tesla invented Elon Musk, or something more surreal took place.”
According to a Wikipedia article, Elon Musk is “a South African-born, Canadian-American business magnate, engineer, inventor, and investor.” In brief, Elon Musk is a living human being.
A brainchild, on the other hand, is “the product of a person’s mind; an idea or invention that is the creation of a particular person, organization, etc.” A fictional character may be someone’s brainchild, but a human being cannot be.
The error of referring to a real person as somebody’s brainchild is widespread enough for Paul Brians to give it an entry in his Common Errors in English Usage:
Some people misuse “brainchild,” as in “Steve Jobs is the brainchild behind the iPhone.” A brainchild is not a person, but the child (product) of someone’s brain. So the iPhone is the brainchild of Steve Jobs.
Buffy Summers (the Vampire Slayer) is the brainchild of Joss Whedon. Microsoft is the brainchild of Bill Gates.
Here are some examples from the Web in which the expression is used correctly:
The Kentucky Derby was the brainchild of Meriwether Lewis Clark Jr. He was the grandson of William Clark (of Lewis and Clark fame).
Jack Kimble is the Congressman from California’s faux 54th District. In reality he is the brainchild of a Chicago school teacher.
The concept of evolution by natural selection is sometimes referred to as Charles Darwin’s brainchild.