Although Wells' career was long  and productive, he wrote his most ground-breaking science fiction novels -- The  War of the Worlds, The Time Machine, The Invisible Man, The Island of Dr.  Moreau, and The First Men in the Moon -- during a short span from 1895-1901. Jorge Luis Borges said that Wells' stories "will be incorporated … into the general memory of the species and even transcend the fame of their creator or the extinction of the language in which they were written."
The greatest American sci-fi writer, Robert A. Heinlein, worshipped Wells and  was heavily influenced by him, including incorporating Wells' enthusiasm for  eugenics into some of his early novels explicitly (e.g., Beyond this Horizon  and Methuselah's Children) and into most of his later novels implicitly  (Heinlein's heroes almost always have some extraordinary mental skill,  especially in mathematics).
The Catholic writer G.K. Chesterton's 1922 book Eugenics  and Other Evils is online, and it's interesting to see what a  nonscientific but extremely sharp observer had to say about heredity during the  heyday of eugenics. Chesterton's basic objection was that individuals should  select whom they are going to marry. It's none of these self-proclaimed heredity  expert's business.
But Chesterton also had a keen eye for just how little the experts knew (or  know), as he showed in this description of H.G. Wells: 
                     
                    Our press  seems to have a perfect genius for fitting people with caps that don't fit; and  affixing the wrong terms of eulogy and even the wrong terms of abuse. And just  as people will talk of Bernard Shaw as a naughty winking Pierrot, when he is the  last great Puritan and really believes in respectability; just as ... they will  talk of my own paradoxes, when I pass my life in preaching that the truisms are  true; so an enormous number of newspaper readers seem to have it fixed firmly in  their heads that Mr. H. G. Wells is a harsh and horrible Eugenist in great  goblin spectacles who wants to put us all into metallic microscopes and dissect  us with metallic tools. As a matter of fact, of course, Mr. Wells, so far from  being too definite, is generally not definite enough. He is an absolute wizard  in the appreciation of atmospheres and the opening of vistas; but his answers  are more agnostic than his questions. His books will do everything except shut.  And so far from being the sort of man who would stop a man from propagating, he  cannot even stop a full stop. He is not Eugenic enough to prevent the black dot  at the end of a sentence from breeding a line of little dots.
But this is not the clear-cut blunder of which I spoke. The real blunder is  this. Mr. Wells deserves a tiara of crowns and a garland of medals for all kinds  of reasons. But if I were restricted, on grounds of public economy, to giving  Mr. Wells only one medal ob cives servatos, I would give him a medal as  the Eugenist who destroyed Eugenics. For everyone spoke of him rightly or  wrongly, as a Eugenist; and he certainly had, as I have not, the training and  type of culture required to consider the matter merely in a biological and not  in a generally moral sense. The result was that in that fine book, "Mankind  in the Making," where he inevitably came to grips with the problem, he  threw down to the Eugenists an intellectual challenge which seems to me  unanswerable, but which, at any rate, is unanswered...
Having given honour for the idea where it is due, I may be permitted to  summarize it myself for the sake of brevity. Mr. Wells' point was this. That we  cannot be certain about the inheritance of health, because health is not a  quality. It is not a thing like darkness in the hair or length in the limbs. It  is a relation, a balance. You have a tall, strong man; but his very strength  depends on his not being too tall for his strength. You catch a healthy,  full-blooded fellow; but his very health depends on his being not too full of  blood. A heart that is strong for a dwarf will be weak for a giant; a nervous  system that would kill a man with a trace of a certain illness will sustain him  to ninety if he has no trace of that illness. Nay, the same nervous system might  kill him if he had an excess of some other comparatively healthy thing. Seeing,  therefore, that there are apparently healthy people of all types, it is obvious  that if you mate two of them, you may even then produce a discord out of two  inconsistent harmonies. It is obvious that you can no more be certain of a good  offspring than you can be certain of a good tune if you play two fine airs at  once on the same piano. You can be even less certain of it in the more delicate  case of beauty, of which the Eugenists talk a great deal. Marry two handsome  people whose noses tend to the aquiline, and their baby (for all you know) may  be a goblin with a nose like an enormous parrot's. Indeed, I actually know a  case of this kind. The Eugenist has to settle, not the result of fixing one  steady thing to a second steady thing; but what will happen when one toppling  and dizzy equilibrium crashes into another.
This is the interesting conclusion. It is on this degree of knowledge that we  are asked to abandon the universal morality of mankind. When we have stopped the  lover from marrying the unfortunate woman he loves, when we have found him  another uproariously healthy female whom he does not love in the least, even  then we have no logical evidence that the result may not be as horrid and  dangerous as if he had behaved like a man of honour.
   
  Indeed, there is now some  evidence that what we call "chemistry" in sexual attraction really is  based on the chemistry of the lovers' respective genomes, such as their immune  systems. People seem to be more attracted to people who smell a little different  from them. Perhaps this is just to avoid incest, or perhaps there's a more  general principle at work that individuals actually do have some sort of sense  of who would "complete them," as they say, but in a genetic  sense.
Somebody who has, say, a strong immune system for repelling Infection X but a  weak immune system for repelling Infection Y, might be better off marrying  somebody with the opposite combination, rather than risk having their children  run into diminishing marginal returns in stomping on Infection X while getting  wiped out by Infection Y. But, at present, we have no idea scientifically how to  measure most of these factors, and it may be that individuals actually do have  some sense, from smell or pheromones or whatever of who is right for them (and  their children).
Of course, there are specific genetic diseases, such as Tay-Sachs. A very  Orthodox rabbi who lost four children to Tay-Sachs started a eugenic testing  service for Ashkenazi Jews that has proved successful in reducing the incidence  of the disease. Of course, he was helped by that his brand of Jewish adherents  tend to have arranged marriages.
Fortunately, fatal hereditary diseases tend not to be all that common for the  Darwinian reason that genes that kill you also kill themselves and thus tend to  die out.
 
My published articles are archived at iSteve.com -- Steve Sailer