The World Health Organization (2020) indicates that sexuality includes sex, gender identity and role, sexual orientation, eroticism, pleasure, intimacy and reproduction, represented and expressed in thoughts, fantasies, desires, beliefs, attitudes, values, behaviors, practices, roles and relationships. In recent years there has been some uncertainty about the terms defining non-normative sexual behaviors, in other words, paraphilias and paraphilic disorders. Since the publication of DSM-III (American Psychiatric Association (APA), 1980), the focus on these behaviors has shifted from a psychoanalytic to an is atheoretical perspective. In the DSM-IV (American Psychiatric Association (APA), 1994) the distinction between paraphilia and paraphilic disorder was already present in the DSM-IV, as it established two sets of criteria. Criterion (A) defined paraphilia as “recurrent, intense sexually arousing fantasies, sexual urges, or behaviors generally involving (1) nonhuman objects, (2) the suffering or humiliation of oneself or one’s partner, or (3) children or other nonconsenting persons, that occur over a period of at least 6 months. For some individuals, paraphiliac fantasies or stimuli are essential for erotic arousal and are consistently integrated into sexual activity. In other cases, paraphiliac preferences manifest only episodically (e.g., during periods of stress), while at other times, the individual can function sexually without such fantasies or stimuli.” Criterion (B) specified that “the behavior, sexual urges, or fantasies cause clinically significant distress or impairment in social, occupational, or other important areas of functioning,” which, together with Criterion (A), constitutes the definition of a paraphilic disorder. The DSM-5 has not significantly altered these criteria, aside from the inclusion of “harm to others…” This perception was also influenced by the late conceptualization of sexology and sexuality research in the 19th century (Beccalossi et al., 2023) and, with it, the term paraphilia, which appeared in the 20th century to eliminate the concept of “sexual perversions.” However, authors such as Moser (2019) discuss how the DSM-5 conceptualises paraphilias and the implications of considering certain sexual behaviors as deviant. Băjenescu (2022) refers to sexual orientation as an internal and stable tendency to have psychological reactions of a sexual nature and desire for sexual relations with persons of a different sex or of the same sex. Sexual orientation has traditionally been classified as heterosexual, homosexual and bisexual, and from a binary perspective. Bogaert and Skorska (2020) refer to relatively stable sexual attraction to persons of the other sex (heterosexuality), to persons of the same sex (homosexuality) or to persons of both sexes (bisexuality). Although there are behaviors that could be called homosexual, for example, an erotic kiss between two men, there are authors who consider that their sexual orientation does not have to be homosexual or bisexual. To understand this, reference is made to Alfred C. Kinsey and his collaborators who between 1948 and 1953 published what is known as the Kinsey Report, which from its results, a scale was elaborated where the minimum score, 0, represented complete heterosexuality and the maximum score, 6, was homosexuality without more; on the other hand, if they obtained between 1 and 5, it was considered bisexuality, with 3 being the degree of complete bisexuality (Kinsey, 1948; Kinsey et al., 1953). In this way, sexual orientation can be seen as a spectrum. That is, it does not only take into account sexual orientation. This allows the authors to consider a person’s sexual behaviors and feelings, placing them on a continuum (Băjenescu, 2022). Over the years, the categories that encompass the term “sexual orientation” have become increasingly more complex and pragmatic (Watson et al., 2020; White et al., 2018), as the concept was previously limited due to various factors that influenced society, such as religion (Beltrán, 2012). Although in recent years there has been a trend towards a decrease in religiosity in Spain (Panadero et al., 2022), there are studies that still confirm that this religious influence is still present (Hone et al., 2020). Swaab (2007) states that sexual orientation can be influenced by a variety of factors, ranging from biological to social.

Besides sexual orientation, one of the other major factors determining sexual preferences and behavior is age (Browning et al., 2000; Herbenick et al., 2010). Most studies found significant changes in some individuals’ sexual behaviors not only over the course of their lives (Caltabiano et al., 2020: Chandra et al., 2013), but also between different generations (Twenge et al., 2015, 2017). Recently there has been a huge discussion about how to classify generations by giving them a label or name depending on the characteristics of the people who make them up. Studies such as those by Rainer and Rainer (2011) and Dimock (2019) state that the generation known as millennials is composed of people born between 1981 and 1996. Centennials, range from 1997 to 2005, considering only those over the age of majority (18 years). The classification of people according to age is done in order to be able to explain why we behave in a certain way from a general point of view.

Regarding the notion of ‘sexual appetite’, which represents a relevant aspect of our work, it will be conceptualised in its meaning of sexual desire. Such desire is constituted as the sum of the forces that drive us towards sexual behavior or distance us from it, oscillating its intensity in a dimension whose poles fluctuate between aversion and passion, evolving notably throughout life (Levine, 2003). Moreover, there may be gender discrepancies in the manifestation of desire, which may affect sexual and partner satisfaction (Mark and Murray, 2012).

The present study focusses on the most common non-normative sexual behaviors such as sadomasochism, which is one of the most popular paraphilias in general population, but is not as frequent as exhibitionism and voyeurism, for example (Bártová et al., 2021; Seto et al., 2021). This would be the combination of sexual sadism and sexual masochism, which according to the DSM-5 (American Psychiatric Association (APA), 2014) would be defined as the feeling of pleasure or sexual arousal when the person is shamed, beaten, tied up or subjected to some kind of abuse; and/or sexual arousal when any kind of suffering is inflicted on another person. Also, another very well-known paraphilic behavior is exhibitionism, in which sufferers experience sexual desire and pleasure by exposing their genitals or having sex in public while being observed (Seeman, 2020). Foot fetishism, bestiality, coprophilia and urophilia, although less common practices have also been included in the study, as they are still relevant for the classification of these behaviors (Krueger et al., 2017; Di Lorenzo et al., 2018). While it is true that some of these practices are more harmful to people’s health than others, they are all considered non-normative behaviors and have therefore been integrated into this study.

To explore the differences between millennials and centennials in appetite for non-normative sexual behaviors, the following hypotheses have been proposed.

In the DSM-I (American Psychiatric Association (APA), 1952), having a sexual orientation non-heterosexual was pathologised in the manual as “sexual deviations.” However, for clinical psychology, this term was replaced by “Egodystonic Homosexuality” in the publication of the DSM-III (American Psychiatric Association (APA), 1980), but was eventually deleted six years later in the review of that edition within the manual.

Considering that it was not until the 20th century that all issues related to sexuality began to be studied (Beccalossi et al., 2023), there have been statistical research that correlate sexual orientation according to age or the generation to which they belong. Based on statistics from different regions, people aged approximately 18–25 years are more likely to have sexual orientations other than heterosexual in both males and females (Copen et al., 2016; Gilmour, 2019). Some studies carried out in the Spanish population, claim that centennials, compared to millennials (Rainer and Rainer, 2011), have a higher percentage of people who are homosexual/bisexual or who are open to trying sex with someone of the same gender (Slebodnik, 2018). It is essential to highlight that in Spain there has been a legal evolution that protects gay, lesbian and bisexual people, for example, the approval of same-sex marriage. As a result, millennials and centenarians have lived through social, historical and political moments that have influenced their openness when it comes to communicating their non-normative sexual orientation. Despite this data, as the years go by, the figures are becoming more and more similar between the two generations.

In recent years, different research has been made into sexual orientation, in which it has been studied whether there are differences in sexual orientation according to different variables such as the role of hormones, evolutionary adaptation, genetics or cerebral and emotional differentiation (Soler, 2005). It has not been until more recently that the influence of age or the generation to which the subjects belong on their sexual orientation has been studied.

Following the same line, it has also been studied how age/generation would not only influence sexual orientation, in this case, on the opinions, attitudes and beliefs that people have towards homosexual and/or bisexual people (Costa et al., 2019; Ekstam, 2022).

According to Cabello (2006), our sexual patterns have changed throughout history according to the political moment in which we find ourselves, since here in Spain, depending on the time period, we have been both in situations of sexual counter-education and in times when we have been able to talk freely about our sexuality.

Along the same lines, the ideological influence of religion in Spain has influenced people’s sex education and is therefore one of the justifications that show us the results of the studies to demonstrate that depending on the generation to which they belong, they will have certain preferences or others with respect to sexuality and thus to non-normative behaviors (Pérez, 2020).

This has led to greater sexual openness among young people over the years. One of the evidences is that in Spain, the average age of initiation of sexual relations with and without penetration has decreased to 16.5 years in 2018. In contrast, in 2010 a study was carried out which stated that the average age in Spain at that time was 17.9 years, which gives us an indication that the younger generation, centennials, is more sexually open than millennials (Díaz, 2010; Moreno et al., 2018).

There is currently an increase in sexual openness in the new generations due to the fact that patterns of sexual behavior are disappearing. In the past, girls were mainly looking for an affective-relational relationship and boys for relationships directly related to sexual pleasure, and were more sexually open than girls (Ballester and Gil, 2006; Browning et al., 2000). This sexual openness has also led to a 149 higher prevalence of risky behaviors today than in previous generations (Dhanoa et al., 2020). A dual pattern was thus established which, although it is more clearly observed in the affective than in the sexual sphere, seems to be changing (López et al., 2011).

However, according to DSM-5 (American Psychiatric Association (APA), 2014), there are 8 types of paraphilias which are sexual sadism, sexual masochism, foretturism, paedophilia, transvestism, fetishism and voyeurism. Exhibitionism, voyeurism and paedophilia are the most frequent paraphilias in men, while in women, masochism is the most common (Joyal and Carpentier, 2017). Sadism, sexual masochism and exhibitionism have been shown to be more likely to be practised by centennials than by millennials (Holvoet et al., 2017).

When we talk about centennials, we are referring to one of the most recent/modern generations and that partly belongs to the 21st century. Thus, according to the study by Cañizo and Salinas (2010), it shows that there is a greater sexual permissiveness, in other words, being more open to having sexual relations or anything to do with sexuality, in young people than in adults.

It has also been shown that Spanish people belonging to this generation are more likely to have a homosexual or bisexual sexual orientation and there are researchers such as Cantillo (2013) who affirms, according to the results of their studies, that homosexual/bisexual people are more sexually open than heterosexuals.

Based on a study conducted among students at the Universidad del Atlántico, homosexual or bisexual individuals and/or couples have a less conventional and more sexually open sex life than heterosexual couples, therefore following the same line, they are more likely to practice non-normative behaviors (Cantillo, 2013).

Although it has been proven that homosexuals/Bisexuals are more likely to engage in this type of sexual behavior, this does not mean that heterosexuals follow a more traditional model, as some authors think, but rather that they are more likely to engage in other types of sexual behavior (Holvoet et al., 2017; Richters et al., 2008).

Sexuality and related behaviors are an essential subject of interest in order to understand and prevent possible risky behaviors and reduce misinformation and stigma, especially among young people (Goldfarb and Lieberman, 2021). Prior studies have already addressed generational differences in appeal of sexual practices beyond the Western cultural hetero-normative framework (Ben Hagai et al., 2022; Campbell, 2022). However, the lack of studies approaching non-normative sexual behaviors in these aged groups, is partially due to the psychopathological conception which relates these behaviors directly to distress and the existence of a risk to the health of the person or their environment (Di Lorenzo et al., 2018), but also because of the disparity in categorising these behaviors (Joyal, 2021; Masiran, 2018). The current study considers an approach in this line, away from the psychopathological component of the behaviors and comparing the appetite for these behaviors without considering it necessary for there to be a negative assessment of sexual preference. We have focused on interest rather than behavior, as some studies have reported one can predict the other (Joyal et al., 2021). While it is true that some sexual behaviors have a psychopathological component, there are other behaviors and desires that could be part of healthy sexual diversity and are widely prevalent in the general population (Joyal and Carpentier, 2021). In order to discuss the results found, this section will be divided in order to respond to the hypotheses suggested.

Despite of the small sample size (n = 332), a significant relationship was found between the sexual orientation of the participants and their generation. This is concordant with what is presented in a large number of studies with wider samples (Twenge et al., 2015, 2017), which help us to support the representativeness of the sample for the other hypotheses. The majority of millennials and centennials claim to be mainly attracted by people with the opposite sex (approximately 79 and 69% respectively), according to a survey performed in the UK (Ipsos MORI, 2020). This paper also reveals that 18% of millennials are attracted to the same sex or consider themselves bisexual, and in the case of centennials this percentage rises to 26%. The Spanish Youth Institute’s annual youth survey, asked about the sexual orientation of young people between the ages of 15 and 29 years old. A total of 77.5% identified themselves as heterosexual and 16.6% identified either as homosexual or bisexual [Instituto de la Juventud (INJUVE), 2020]. Both studies mention the globalisation, the decrease in social stereotypes and equality policies as possible factors involved in the sexual liberation of centennials. These statistics are similar to those found in the study sample. In this case, the differences are also greater among millennials (73.6% heterosexual, 26.4% homosexual or bisexual) than among centennials (84.4% heterosexual, 15.6% homosexual or bisexual), with the overall result being somewhere in midpoint (79.2% heterosexual, 20.8% homosexual or bisexual). According to these results, the sample of the present study can be considered representative in relation to the sexual orientation of the participants, and the following hypotheses can be taken into account with this consideration in mind.

As can be seen in the results section, this study did not find a statistically significant difference, according to the results obtained, between the two generations in most of the non-normative sexual behaviors explored, which is not in line with the conclusions reached by López et al. (2011). Among the reasons which may argue these differences, there is the historical timing in which each study has been carried out. Even though the results of López et al. (2011) were found just over a decade ago, it is probable that the differences between generations at that moment in time were more accentuated than they are nowadays.

Nevertheless, there were significant differences between the appetence of both generations for behaviors related to voyeurism and exhibitionism (items 11, 12, 13 and 14) and behaviors related to foot fetishism (items 23 and 24). Within all of these behaviors, appetence marks were higher in the millennial group than in the centennials. There is no consistent evidence in the literature to justify these differences. However, it is probably due to the differences in digitisation between the two generations (Quincy and Manduza, 2021). Millennials dealt with the digitisation of society during adolescence and young adulthood, while centennials were born into a fully digitised world with access to the internet from an earlier age (Kaviani and Nelson, 2021). Premature exposure to stimuli that could be perceived as sexual may have affected centennials’ capacity for excitation and appetite for images of nudity or sexual scenes (Carvalho, 2021). This added to the fact of living in a more open society for the exploration of sexuality and the decreasing age at which the first sexual relations took place (Neff, 2020) can also explain the reduced desire to be seen undressed or to be observed having sex. Early exposure to pornography may also explain differences in sexual appetite to images of nudity or having sex (Massey et al., 2021), particularly with centennials having greater exposure to pornography at a younger age than millennials, who may be more sensitive to such content due the lack of early exposure to it (Ningrum and Kusbaryanto, 2021). In addition to the consumption of pornography, the increased use of mobile devices among teenagers has facilitated the development of sexual behaviors aimed at sharing nude images or videos or engaging in behaviors related to erotic self-stimulation such as sexting, which could contribute to the desensitization of millennials to seeing other people naked or engaging in sexual acts (Crofts et al., 2016; Raine et al., 2020). Another possibility is that the appetite for these paraphilic interests/behaviors may appear later in life (Chandra et al., 2013). Regarding the millennials’ increased appetite for foot fetish-related behavior (items 23 and 24), it could be explained by the rise of extreme and atypical content included in sexually explicit internet material (SEIM), especially content related to fetishism and other dominance/submission behaviors (The Economist, 2015). Such content can serve as models or scripts for sexual behavior among young people (Frith and Kitzinger, 2001). Thus, repeated exposure to pornography can give rise to sexual scripts where certain sexual behaviors, sexual roles, gender stereotypes, and attitudes are normalized and promoted (Ryan, 2011).

Regarding the third hypothesis, which concerns the differences in the appetite for more varied non-normative sexual behaviors in centennial participants compared to millennials, taking into account the variable of sexual orientation, the influence of sexual orientation on the appetite for different non-normative behaviors is confirmed. The non-normative behaviors that showed significant differences were the same as those in the second hypothesis (items 11, 12, 13, 14, 23, and 24), along with the appetite for practicing asphyxia (item 10), the desire or reality of having sex with animals (item 15), and seeing someone urinate on another person or urinating yourself on another person (items 18 and 19).

On the one hand, these results could be in line with those found by Cañizo and Salinas (2010), as there seems to be a greater appetite for non-normative sexual behaviors in younger people. Additionally, these findings support what Hunt et al. (2019) pointed out, who found a greater appetite for a wider variety of non-normative sexual behaviors in people with a homosexual or bisexual sexual orientation.

The appetite for engaging in asphyxia was found to be greater among homosexual/bisexual groups in both generations. This increased appetite may be due to the high prevalence of sexual aggression-related behaviors, including asphyxia, in gay pornography (Fritz and Bowling, 2022). Consumption of this type of content can lead to learning and an increased likelihood of replicating these behaviors in sexual practice. However, this type of content is more commonly found in pornography aimed at heterosexual audiences, in which aggression is typically directed towards women (Carrotte et al., 2020). Consumption of this type of content has been shown to influence the sexual behaviors of young people (Herbenick et al., 2022), with women and transgender/non-binary individuals being more likely to have been strangled than men. Further research is needed to understand the relationship between sexual orientation and the appetite for engaging in asphyxia in order to draw more comprehensive conclusions regarding the results of the present study.

Regarding the desire to engage in behaviors related to bestiality, it is centennials with a homosexual/bisexual orientation scored higher compared to other groups. These results may be related to the furry phenomenon, known as the sexual and affective attraction to anthropomorphic animals, cartoon animals, or people dressed as animals. Hsu and Bailey (2019) surveyed 334 men identified as furries to ask them questions about their sexual orientation, sexual motivation, and sexual interests. A large majority of our sample identified as non-heterosexual (84%) and reported some degree of sexual motivation to be a furry (99%). Although this phenomenon appears to have non-sexual motivations that have a greater impact on identification with the group members of this phenomenon (Brooks et al., 2022).

Regarding behaviors traditionally conceptualized within urophilia, such as watching someone urinate or being urinated on or urinating on a partner, homosexual/bisexual millennials were the group that showed the greatest appetite for these behaviors. If access to extreme, abnormal, or domination/submission-based pornography is becoming more accessible (The Economist, 2015), this may explain a greater desensitization of young people to such practices. According to a study by Vandenbosch (2015), adolescents are more exposed to sexually explicit internet material (SEIM) related to affectionate themes, while young adults are more often exposed to SEIM related to domination themes. Consequently, millennials appear to be more likely to be exposed to pornography with themes of domination and violence than centennials. This greater exposure to domination content could explain the greater appetite of millennials for behaviors related to foot fetishism and urophilia, although the relationship of the latter to sexual orientation has not yet been thoroughly explored.

In summary, no differences were found in the inclination to engage in most of the non-normative sexual behaviors studied between generations. However, it seems that sexual orientation is a variable that can help better assess these differences. These results can be very revealing about contemporary Spanish society, where understanding these behaviors from a perspective that moves away from the psychopathological approach can help design better education programs on sexual diversity without the usual restrictions based on prejudices and taboos (Pomeroy, 2017). In any case, further research with larger samples is needed to confirm or refute the findings of the present study.

However, we do conclude that there is a need for research that explores how to improve sexuality education programmes in Spain, from a holistic perspective with sexual and gender diversity, in order to increase the levels of physical, mental and sexual health of society as a whole.