What you learned in school
Psychology textbooks listed homosexuality as a "sociopathic personality disturbance" and later as a "sexual deviation" in the DSM. Students learned that it was a mental disorder requiring psychiatric treatment and that various therapies could "cure" homosexual patients. Medical schools taught future doctors that same-sex attraction indicated psychological maladjustment.
What we know now
Psychology textbooks classified homosexuality as a mental disorder that could and should be treated or "cured." Students learned about various conversion therapies and psychological treatments. The American Psychiatric Association removed homosexuality from the Diagnostic and Statistical Manual of Mental Disorders (DSM) in 1973, recognizing it as a natural variation of human sexuality. This change was based on scientific research showing that sexual orientation is not a choice or mental illness. Conversion therapy has been discredited and is considered harmful by major mental health organizations.