Sexual Deviance is one of many 'clinical' and 'legal' terms that has made it's way into common usage.
To truly appreciate the origins of such terms it's important to first reconsider what the term 'deviance' means and even the term 'sexual'. It can almost be guaranteed that others do not generally agree with you in regards to these meanings which most consider 'self evident'.
They are not.
First, sexual connotes many meanings with various shades and greater complexity in whatever context the word finds association.
The term 'Sex' is itself a word that is changing and no longer can be assumed to have a 'universal' meaning.
A joke exists as most do to bring attention to the limits of our comprehension. In this particular sexual joke a man is asked to state his sex and respond's 'no' or 'none' because he has never considered it in terms of general but solely as a 'condition' one has or doesn't have. The examiner is reasonably perplexed.
This confusion abounds today. Most of the confusion exists between those who believe in an 'innate' morality which they claim 'they have' or 'my morality' versus 'your morality'. These discussions are not new and go to the origins of ethics in the debates of Plato, Aristotle and the teachings of early church fathers and later debates of enlightenment.
Sex itself can be an 'adjective' , a 'verb', a 'noun'. Alone it is uncertain what it actually refers to. All of this is neither good, bad, right , wrong or inherently evil.
It is merely a reflection of the changing times. It is a fact that the word has changed in use, meaning and continues to change. Yet those who don't comprehend the transitional nature of language, that culture is changing and attitudes change and that there is no 'agreement' on whether the change is evolution or devolution, universal or local, have serious 'opinion's' and even more commonly speak with the authority once associated with only the queen, as in Queen Victoria, "we are not amused".
The once "catholic" and universal society has become segmented and insular with a variety of associated languages and more importantly dialects which reflect less 'regional dialectism' but rather as 'cultural'.
Sex has different meanings to different classes, to different cultures and too different ruling hierarchies.
Consequently the adjective 'sexual' is at first glance a non sequitur. It's vague and non specific. Clearly it does not refer to the gourds though with the consideration of 'fetishism' it may well.
With just this consideration, deviance is even more historical. The term 'deviance' or even the more recent clinical term "disorder' assumes all manner of attributes such as 'normal'.
Normal to the moralist is a highly different 'normal' than that of the epidemiologist.
Further, the law courts inherrently are involved in maintaining the status quo and serving the authority which exists only in the status quo. Hence the attribute of 'normal' must serve the most abnormal 'ruler' and apply more seriously to the majority. The economic division of rich and poor with the greatest wealth distributed with power to the fewest possible individuals causes the 'value systems' associated with words like 'deviance' or 'disorder' to have a wholly different context.
"Steal a little and they put you in jail, steal a lot and they make you king," is a Dylan paraphrase of English philosopher Dr. Johnson's famous words.
In the clinical setting and the textbooks accepted in the university, sexual deviance has simply referred not to the behaviour of the wealthy and ruling class but rather to those that aren't.
When I worked in Saipan the law courts had been paid for by a famous gentleman known for his charity and contribution to the islands who also loved to have sex with little girls. Like the men of the old testament who had several wives or committed adultery or didn't have sex at all their 'sexual deviance' was 'judged' in relationship to other aspects of their lives.
The present 'sexual offender' lists are like most laws not for the likes of presidents but for those who cannot afford lawyers, the majority, or justice, the majority, in societies which fall far short of any ideals of society that various 'utopians' have announced.
That said 'sexual deviance' is a term I choose to use for sexual practice or behaviour since in an historical sense all sexual behaviour has at some time or other been denigrated. Even in herterosexual marriage sexual behaviour can be deviant and missionary position sex with devious regularity may itself come under the purvey of the age old 'thought police' and may or may not fall afoul of 'political correctness'. Indeed , many 'feminist lesbians' consider the church and state sanctioned 'marriage' as 'sexual abuse of women'. Masculinists have in turn called this 'institution' of 'normality' 'state prostitution'.
Modern and post modern scientific researchers have meanwhile concluded that the variety of sexual behaviours of humans is as diverse as that of the birds which according to those researchers have demonstrated every form of sexual congress and behavior imaginable and certainly more than any non ornithologists might imagine.
So I use the term sexual deviance as a means to group sexual behaviour and discuss the behaviour with consideration of it's place in context and time. Today sexual deviance might well be considered the norm or inclusive term. Those who practice missionary posiiton heterosexual monogamy (mphm) a significant minority today, would be considered 'sexually deviant' by the normative standards used at the time the terminology originated. So either our grandparents generation are collectively deviant by present day standard or the terminology should adapt to what is normative and perhaps take into consideration modern and post modern concepts of "consent", "do no harm", "adult" etc. In this way 'masturbation' once thought extremely sexually deviant would not today be group with pedophilia which morally and ethically is still considered very deviant.