Burr discusses biological research on sexual orientation by scientists such as the neuroscientist Simon LeVay, the psychiatrist Richard Pillard, the psychologists J. Michael Bailey, Heino Meyer-Bahlburg, and Anke Ehrhardt, and the geneticist Dean Hamer.

[13] Olson credited Burr with writing about science well and with covering the arguments of both supporters and critics of biological explanations of sexual orientation and the associated political issues.

[5] Cytowic credited Burr with "disclosing the political meaning of sexual-orientation research" and with "revealing the media's absurd questions and abysmal grasp of science.

"[8] Anderson wrote that Burr provided an "absorbing and comprehensive" discussion of biological research on sexual orientation, and a clearly written "reader-friendly interpretation" of the topic, with a broad presentation of recent findings.

She wrote that A Separate Creation contained "little analysis and lots of hype", but credited Burr with speaking to many researchers interested in searching for a biological basis to homosexuality, and concluded that the book was worth reading, "If you can stomach this sort of thing".

[10] Porter called A Separate Creation a dispiriting comment on the state of science, writing that sexual orientation researchers have made exaggerated claims based on limited and sometimes flawed evidence.

[18] Mass considered Burr a "gay-positive essentialist" and A Separate Creation "a valuable historical document" comparable to the journalist Randy Shilts' And the Band Played On (1987).

He noted that scientific study of the determinants of sexual orientation dates to the 19th century and that many investigations of the possible biological basis of homosexuality preceded LeVay's work.