But as to secondary sex-characters they differ from both.
"Taboo and Genetics" by Melvin Moses Knight, Iva Lowther Peters, and Phyllis Mary Blanchard
SEX, secondary characters of, latent, ii.
"The Variation of Animals and Plants Under Domestication, Volume II (of 2)" by Charles Darwin
No mental trait has ever been proved to be sex-limited in inheritance, or to exist as a secondary sex character.
"Vocational Psychology: Its Problems and Methods" by Harry L. Hollingworth