This know also, that in the last days perilous times shall come.  For men shall be lovers of their own selves, covetous, boasters, proud, blasphemers, disobedient to parents, unthankful, unholy,  Without natural affection, trucebreakers, false accusers, incontinent, fierce, despisers of those that are good,  Traitors, heady, highminded, lovers of pleasures more than lovers of God;  Having a form of godliness, but denying the power thereof: from such turn away. [II Timothy 3.]
Yet, for all that, among the Victorians was an obsession with they perceived as a crisis of degeneracy unique in its degree and different in its kind. To give a slightly trivial example, the tang of degeneration is part of the piquancy contributing to the enormous popularity of the Sherlock Holmes stories. A much better piece of evidence is ... Marie Corelli! The unmatched popularity of her fiction and its immediate and uniform concern with degeneracy is very strong testimony to the zeitgeist. I own a copy of one of the better scholarly treatments of the matter,
Degeneration, Culture, and the Novel, 1880-1940 by William Greenslade, which I will put on course reserve.
Reasons for the obsession with degeneracy among Victorians, ones that cut across class, sex and income, are manifold and over-determining. Ordinary fin de siecle consequences are of course important. Additionally, a technological explosion had originally driven the Industrial Revolution which at once created a working class and forced it into urban concentrations. The resulting slums throughout the proliferating major cities -- Manchester, Bradford, Leeds, Birmingham, Newcastle, &c. -- ignored hygiene and bred disease and ignored social welbeing and bred vice: gambling, prostitution, brawling and drunkenness. Victorian England was the high water mark of Methodism and Evangelicism and its crusade for social reformation was uniquely intense. Slavery and child labour were abolished; fourteen-hour factory work days were reduced for women; prisons and hospitals, through campaigners such as Elizabeth Fry and Florence Nightingale, were made more humane. The Salvation Army campaigned to counter alcoholism and other vices. And the ever-intensifying technology of the Industrail revolution was turned, by reformers, to improve drainage, sewage and potable water systems.
To this social atmosphere I would add an element that I have not yet fully defined nor mapped the origins of (beyond its evolutionary connection to Puritanism), but which amounts to an aesthetic, emotional and an erotic preference for hid delights. It can be contrasted with an Age -- such as ours perhaps -- which prefers things revealed and decries restraint. The Victorians were titillated, and comforted, by what was known to exist but was draped from universal sight.
Add to this the intellectual earthquake which was Darwinism: a theory taken as a justification for progress and improvement -- the progress and improvement, that is, which is so much the character of Victorianism. The intellectual climate, then, produced a cast of mind which can be termed, not merely progressivist, but outright perfectibilian.
These, and indeed other, aspects of the Victorian Age, then, made it intensely (I don't say uniquely) expressive when developments which are comprehensibly termed "degeneracy" became evident. And thus it has become a commonplace among scholars of the Nineteenth Century to take obsession with degeneracy as a salient characteristic of the times.