When how where did sexual orientation originate?

Answer 1

It was a phrase coined by the American Psychological Association in the mid 1960's to 1970's.

But the actual concept of sexual orientation was invented in America in the late 19th century. The term "homosexual" was invented at this time, as was "heterosexual." Prior to this time period, people were not considered to have "sexual orientations." In fact, anti-sodomy laws (forbidding non procreational sex) included sex between people of the opposite gender and people of the same gender. Foucault states that upon the invention of the term "homosexual" a "new species" was born. Homosexual were considered to be "aberrations" or mentally ill. It was a clinical term for what was seen at the time as a disorder.