Some people become sexually aroused by an object or part of the body that's not typically considered sexual, such as feet or hair.

Others may develop a liking for a particular lifestyle that allows them to live out their fetish or interest in erotic role-playing, such as bondage, dominance, submission, and sadomasochism (BDSM). Think “Fifty Shades of Grey.”

Fetishes and alternative erotic lifestyles come in a wide variety of forms, from common to extreme.

Consider John-Michael Williams, owner of Tykables, an adult baby fetish shop in Illinois that sells adult diapers to people who are aroused by being treated like babies.

Williams says he wears adult diapers around the clock for comfort.

“I don't consider it a fetish for me because there are a lot of the different aspects of the ABDL [adult baby diaper lovers] community that attracted me to it,” Williams told Healthline. “The only real sexual aspect of it is being attracted to a specific underwear type. I relate it to an underwear fetish. Seeing a good-looking guy in a pair of briefs or a good-looking guy in a diaper, either way it's seeing a good-looking guy in a pair of underwear, just a very specific type.”

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But is it a mental illness?

Could people prone to fetishes like Williams suffer from mental illness or trauma?

Dr. Richard Krueger, associate professor of psychiatry at Columbia University Medical Center, says some people who practice fetishes or alternative erotic lifestyles may be mentally ill, or have experienced trauma. But he says this is not a predictor.

"With all the paraphilic disorders or matters of sexual interest that don’t involve typical sexual objects or behaviors, we can question how the behavior develops and what might this involve in terms of a lifestyle, but many of these questions are open-ended," Krueger told Healthline.

He adds that a number of studies show people who practice BDSM have a higher level of socioeconomic functioning compared to control groups.

“The literature is limited, but it would suggest that they’re healthy or healthier,” Krueger said.

Williams says some of his clients suffer from an autism spectrum disorder, such as Asperger’s syndrome, and get positive sensory feedback from wearing a bulkier diaper.

“In these instances, they are not into the sexual fetish side,” he said. “However, most of our clients are mentally sound, and for a lot of them the lifestyle is not about sex. It’s about relaxation and stress relief and taking aspects from childhood, a time when life was simply easier. Obviously our brand is an extreme of that, but the concept is the same.”

A 2014 paper published in the Archives of Sexual Behavior looked at ABDL. Nearly 2,000 people who practice ABDL completed an online survey. Answers from some respondents — mostly men — showed that ABDL behaviors were associated with attachment styles and parental relationships.

For instance, for male respondents, being more anxiously attached was linked to nine ABDL behaviors, including a desire to be dominated and to have a “daddy” (the role of the person nurturing the adult baby).

Furthermore, some male respondents who reported having a negative relationship with their mother or father showed a connection to engaging in sexual activity with a mother or father figure.

On the other hand, those respondents who had a positive relationship with their mother or father viewed diapers as sexually stimulating, and placed more emphasis on sexual enjoyment from their ABDL activities.

“Different people have different reasons for being involved in the fetish or lifestyle. There are those who are into it for the sexual gratification, and that can be widely varied even by itself. For some people it can be degrading and where they want to be embarrassed or even very BDMS in nature. And for others it isn't sexual all,” said Williams. “The only common denominator is the diaper is involved.”

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Preference and personality

Experts say there is a wide range of fetishes because there is a wide variety of people.

“Sexual fantasy is highly varied across the spectrum, so fetishes might simply be one element of our diversity in terms of sexual interest and arousal,” Jessica O'Reilly, Ph.D., a sexuality counselor since 2001, told Healthline. “That means we'll have different tastes just like we do in food.”

Krueger concurs.

“Generally speaking, a typical case may be somebody happens upon an object by accident or through exposure to leather, or dolls, or part of a human that's nonsexual, such as a foot or toe, and finds it pleasurable, so they continue using it in a sexual way,” he said.

O’Reilly adds that some people are more easily aroused than others.

“There's a theory that these people may be more open to developing fetishes … because they’re sexually excited more easily,” she said.

Personality possibly plays a part, too.

For instance, according to a 2014 survey published in the Canadian Journal of Human Sexuality, which looked at the personality traits of 270 people who practice BDSM, those who prefer the dominance role to the submissive role identified themselves as having different traits.

Dominants scored significantly higher than submissives on desire for control, extraversion, self-esteem, and life satisfaction. Submissives scored significantly higher than dominants on emotionality.

Both groups scored similarly on empathy, honesty-humility, conscientiousness, openness to experience, altruism, or agreeableness.

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Early experiences

Sexual experiences during or around puberty are another factor that can lead to fetishes.

“If an object was pleasant or salient to early sexual experience we may associate that object with sex, and the use of it continues on with sexual behavior,” said O’Reilly.

So was the case for Williams.

While he can’t pinpoint exactly when he became interested in the ABDL lifestyle, he recalls looking at pictures of men in underwear on the internet when he was around 16 years old.

“I think the first time that I ever saw a guy in a diaper was during that phase. While looking at hot guys in underwear, I came across one in a diaper,” he said. “I already knew that I liked the idea or aspect but never thought that there were other people out there who also enjoyed it, not only from a sexual aspect, but just in general.”

O’Reilly compares this to connections with odors.

“You can recognize and associate certain feelings with smells 20 years later. Maybe they’re comforting feelings like that from a perfume your mother wore, or perhaps they’re destabilizing like the smell of a cologne an ex used to wear,” she said.

Either way, she says smells continue to bring about memories and feelings throughout one's life.

A connection between the mind and body also has an impact, says O’Reilly.

“Every sexual experience is generally physical and psychological. As we learn to associate an object or experience with arousal, the two become tied together, so ultimately we develop fetishes through experience,” she said.

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When is it a problem?

Once people develop a fetish or interest in a lifestyle, Krueger says how they fulfill their desires determines if it’s healthy behavior or not.

“Many suffer in silence and do nothing about it,” he said. “Some people will find pornography that suits their particular interest and turn to that. Others will develop compulsive usage and it becomes out of control, but that's generally unusual. And others will find people who share the same interest.”

The Diagnostic and Statistical Manual of Mental Disorders (DSM), published by the American Psychiatric Association, states that most people with atypical sexual interests do not have a mental disorder.

The manual says to be diagnosed with a paraphilic disorder people with these interests must demonstrate the following:

  • feel personal distress about their interest, not merely distress resulting from society’s disapproval
  • have a sexual desire or behavior that involves another person’s psychological distress, injury, or death, or a desire for sexual behaviors involving unwilling persons or persons unable to give legal consent.

Krueger notes that the topic still leaves many open-ended questions and more research is needed. He believes Charles Darwin said it best in 1862 when he stated, "We do not even in the least know the final cause of sexuality. The whole subject is hidden in darkness."

“There’s not much more to it than that,” said Krueger.