This is a bizarre story, with this anecdote, in particular, being telling about Professor Roberts, the psychologist from Stanford:

In his paper responding to Hommel and Roberts, [Lee] Jussim employs an analogy, drawn from a quote in Fiddler on the Roof, about a horse and a mule. He writes that mixing science and ideology is like selling someone a mule when what you promised was a horse. Because Roberts’s paper is both scientific and ideological, according to Jussim, it is a rhetorical hybrid — i.e., a mule.

Roberts, who identifies as Black and multiracial, writes in his paper that comparing people of color to mules is a “well-documented racist trope,” though he gives Jussim the “benefit of the doubt” and doesn’t directly assert that Jussim is advancing that view. I spoke with Jussim, who told me he was unaware of that history, and he points out that his paper begins by quoting the well-known musical. “It’s absurd because obviously the origin is Fiddler on the Roof,” Jussim says. “It refers to an idea. It doesn’t refer to people.”

Jussim is obviously correct, and Roberts should apologize to him.