Short answers, pulled from the story.
The word heterosexual emerged from a specific moment in 1869 when Karl Maria Kertbeny coined the term alongside its counterpart homosexual. These terms did not enter common use until decades after their creation, with Richard von Krafft-Ebing and Albert Moll reintroducing them around 1890 for wider scientific discussion.
The prefix hetero derives from the Greek word héteros meaning other party or another, while sex comes from Latin words describing characteristic sexual differentiation. The abstract noun heterosexuality itself was recorded for the first time in 1900, and Merriam-Webster listed the word in 1923 as a medical term for morbid sexual passion for one of the opposite sex.
A 2012 Gallup poll concluded that 96.6% of all U.S. adults identify as heterosexual with margin of error plus or minus 1%. A 2015 YouGov survey of 1,000 US adults found 89% sample identified as heterosexual, while UK Office for National Statistics survey in 2010 found 95% of Britons identified as heterosexual.
The term heteronormativity was popularized by Michael Warner in 1991 introduction Fear Queer Planet published Social Text journal issue 9 number 4 pages 3-17. Feminist Adrienne Rich argues compulsory heterosexuality is a continual repeating reassertion of heterosexual norms in her article published in 1980 on pages 631-660.
Scientists believe a combination of genetic hormonal and environmental factors determines sexual orientation without any single factor proving conclusive. Factors related to heterosexual development include genes prenatal hormones and brain structure interacting with the environment, where estradiol and testosterone catalyzed by enzyme 5α-reductase into dihydrotestosterone act upon androgen receptors in the brain to masculinize it.