Until 1973, homosexuality was globally classified as a mental disorder, with others and ultimately the World Health Organisation following in 1990 in removing this classification. The description of homosexuality as an 'unnatural' form of behaviour started as early as the 12th century, and it was featured in the Diagnostic Statistical Manual (DSM) in 1952 as a mental disorder. 
A mental disorder is by definition a mental condition which causes issues making it hard to impossible for the affected individual to lead a normal life. A requirement for something to be classified as a mental disorder is that it has to cause 'dysfunction', i.e. symptoms which are not caused by merely a preferences or a temporary state of mind, such as grief.
Why homosexuality was classified as a disorder (and still is by some), is that it is the displaying of behaviour which runs contrary to what was dictated and ultimately expected. This expected behaviour being heterosexual behaviour and attraction. Anyone not displaying the correct behaviour was thus said to have a mental disorder. Pretty simple and easy. And also hopelessly wrong, of course.
What I really want to address with this article is not homosexuality and its classification as a disorder, but to use it as an example of how mistaken people can be, even if it is with the best of intentions. Those who put homosexuals through 'therapy' over the past hundreds of years would usually not have done it with any kind of malicious intent, even if the result was the same.
The exact same thing is happening today with intersex individuals. While previously largely ignored or brutally forced through 'normalisation' surgery (akin to 'gay therapy' in many ways), quite recently (past few years), there is a movement within the medical world to rename 'intersex' to 'disorder of sex development' (DSD).
If we look at the medical conditions intersex people deal with, we can see that by and large none of them are troubled by it. Normal bodily functions take place, they grow up with normal brains, normal intelligence. They are all rather boring and uninteresting from a medical point of view. Only thing that might be different in some cases is the endocrinological and reproductive formation and development, but this rarely necessitates any kind of medical interference.
Yet every day at least one intersex infant forcefully undergoes this 'normalisation' surgery, in order to remove any trace of being intersex. A sex is forcibly assigned, despite there being no scientific grounds for assuming that this is anything but a wild guess. A preference for physical sex and gender role is not encoded in one's genes after all, or the world of transsexuality would look very different than it does today.
The real reason why physicians and parents would genitally mutilate infants is because the topic of intersex is as embarrassing to them as it was to have a non-heterosexual child years ago. Or still today for some. As homosexuality is slowly becoming an accepted thing in societies around the world, intersex is still something which is seen as something which does not belong in a binary society.
For sex must be binary. Society has accepted homosexuality, because it doesn't break the sex binary. It has accepted transsexuality, because it doesn't break the sex binary. Neither of them upset the delicate balance of having just men and women.
Intersex destroys all of that. It shows that sex isn't a matter of absolutes and extremes, but a spectrum. As any zygote in a pregnant woman's uterus is initially female, this shift towards becoming 'male' is a gradual process, requiring many chemical triggers and other signals to be released and started at the right time. In the case of a chimera (mixed genetic material, e.g. from multiple zygotes), the end result is unpredictable.
If society were to accept intersex, it would have to abandon its concept of male and female. It would have to rethink and reshape itself completely from the ground up. Entire bureaucratic systems would have to be scrapped and rebuilt.
Societies are about inertia and will perceive any rapid change as a threat. This is why homosexuality got marked as a threat within the highly conservative Christian medieval times. This is why intersex has largely only ever been accepted by small, scattered societies around the world.
This is why intersex has been marked as 'disorder'. Not because those physicians care about us intersex individuals. On the contrary, they couldn't care less about us. What they do care about is the preservation of the status quo. The only way they can continue to keep erasing traces of intersex features in infants and children is by coming up with a new justification now that the world is becoming aware of intersex.
This justification is through redefining it as a disorder, which gives them all the legitimacy to continue these experimental 'normalisation' surgeries. Because they aren't harming us intersex individuals, but 'helping' us, as growing up intersex would be a traumatic experience. Or so they claim.
I'm sure they believe every word they say and may really think that they are helping us, but really... it's still pretty darn evil what they are doing.