When it comes to sexual fetishes, many different processes take place inside the brain that triggers the attraction. Most people are obsessed with individual parts of the body, while non-living objects sexually arouse others.
It can be difficult to study sexual fetishes because people are naturally shy about discussing them, but by studying search queries crowd-sourced by online search engines, researchers can learn quite a lot about what people won't share in person.
The search query data hinted that it wasn't just body parts that triggered sexual desires in people, but even objects associated with said body parts seemed to fit the bill. Worthy of note, the infamous foot fetish was one of the most popular searches from the crowd-sourced data.
Studies also illustrate how a phenomenon known as sexual imprinting impacts a person's sexual desires throughout life. In this process, a person "learns" what they would prefer in a desirable mate through their life experiences, so the way a person grew up can influence their sexual desires.
While sexual fetishes are often thought as taboo and were once considered mental illnesses, modern science argues that it's healthy to have one if it doesn't harm the person or their partner in the process.