The Solitary Sin (1919)

Bob, John, and Edward--three young boys growing up in the same neighborhood--have vastly-different experiences with sex. Bob's father patiently explains "the birds and the bees" to him, and even takes him to a hospital to see the effects of venereal disease. John's and Edward's parents don't tell them anything, leaving the boys to find out "on the streets". Consequently, when they become adults, John--who's been "playing the field"--contracts syphilis and is stopped from marrying and infecting his sweetheart. Edward, on the other hand, has become addicted to "self-love" and masturbates himself into an insane asylum. Wholesome Bob marries and, naturally, lives happily ever after.