[Fantasywriter]

Apparently the word has an unfortunate etymology:

‘”MULATTO” IS A DON’T

Mulatto arguably has the ugliest roots of the antiquated terms on this list. Historically used to describe the child of a black person and a white person, the term reportedly originates from the Spanish word “mulato,” which, in turn, originates from the word “mula,” or mule—the offspring of a horse and a donkey. Clearly, this term is offensive, as it compares the union of human beings to that of animals.’

https://www.thoughtco.com/avoid-these-five-racial-terms-2834959

[The link goes to a very liberal site, so take the information with a grain of salt.]

[dr_lew]

Clearly, this term is offensive, as it compares the union of human beings to that of animals.

I believe it was Mark Twain who opined it was the animals that might rightly take offense at such comparisons.

[Fresh Wind]

Clearly, this term is offensive, as it compares the union of human beings to that of animals.

Humans ARE animals.