There are still many people in the world who for religious or superstitious reasons maintain what we may call "strict sexual morals", and who consider "sinful" many practices to which they attach a label of "perversion". This idea still predominated with a spurious scientific appearance until the 70's of the past century, and it was so much so that commonly accepted sexual practices coincided almost perfectly with old religious commandments.
Things have changed in most advanced countries, and few people in them would consider morally wrong any kind of sex, excepting whatever includes violence, abuse and harm to oneself or others, and this is exactly what makes churches so nervous. While they could maintain that their generally anti-sexual morals were "natural", "universal" or "scientific", they could also impose their laws to whole societies ready to accept them, but when their concepts appear more and more as beliefs dictated by the faith of a minority, they are the only ones to consider perverse what for others is simply recreational.
For me it's in fact the other way around: sex is a very natural need, a powerful drive to which few humans escape. To deny, suppress or enclose it in a fence of fastidious regulations creates anxiety, hypocrisy, guilt and unintended effects, such as obsessions, addictions and real perversions.
What is more perverse than the consideration of sex as a purely reproductive function? It amounts to condemn most people to live guiltily, as thougts and actions have never adjusted to this narrow and certainly inhuman ideal.
An example: how can a Roman Catholic couple have a child by artificial insemination when this is necessary?
1. The man may not masturbate to obtain semen
2. The couple may not use a condom to keep semen during intercourse.
The couple may use a condom previously perforated by a needle. In this way most of the thick seminal fluid remains inside, but the possibility of impregnation still remains.
What a twisted mind can elaborate such scenarios?