I saw this surprising assertion in a Slate comments section in reference to an article on Twin Studies. I did not see anything on thisin his wiki. Do these assertions have any truth to them?
I don’t know about Gould deliberately committing falsehoods, but I do think he tended to be a victim of the very thing he liked to criticize – unconsciously slanting the data to fit one’s preconceived notions. I noticed this in his book Wonderful Life. It’s about the fossils in the Burgess Shale. He makes a big deal about how the early scientists went beyond what they actually found and “filled in details” to shoehorn the fossils into conventional taxonomic classes. But the book is filled with lovely “artist’s reconstructions” of what Gould himself thinks the animals “really” looked like, which take at least as much liberty with the actual fossils as any of the earlier efforts did. (I still love the book, by the way.)
edit: nevermind!
Which to his credit he did own up to in later essays about the Burgess Shale but I did wonder why he did so anyway to start with. The reader of Gould, of course, would have been well advised to take into account that he would himself be vulnerable to that pitfall – and the writer should not have to explicitly remind the reader “be skeptical of ME, as well”, it should proceed naturally.
As to the “unraveling” of Gould, one has to be careful in that he did “make enemies” both academic (e.g. the whole “Punk Eek” debate) and ideological (e.g. his “NOMA” proposal of coexistence between church and science is virulently despised by many critics), and there are those who would not be satisfied with his fading away and his theories and reputation not standing the test of time, but who want him taken down hard.
I think he’s also famous for disingenuously saying about “belief” in God that it is legitimate as a comfort even when we don’t actually think it’s true. IIRC this was during a Kansas radio interview. I think that this shows he was actually adopting the atheist stance he argued against.
I do not recall Gould’s criticizing this as much as remarking it is unavoidable.
Gould, unlike many scientists, acknowledged that observations are made in a cultural context, and that conclusions frequently are colored by cultural expectations. Mediocre scientists have viewed this as an attack.
He was also quietly polite to everyone at the corner store on the few times I encountered him.
Gould has always been controversial, and has enemies both on the political right (basically, those who like to believe that success in life is a sign of intrinsic, innate merit) and on the left (mainly ‘new’ atheists, who think that anyone who does not think all religious believers are stupid and evil must themselves be stupid and evil). He also made scientific enemies amongst people like IQ researchers, because, if he was right, their work was revealed to be pseudoscience. Needless to say, people who have devoted their lives to a certain sort of research will fight tooth and nail against any such ‘debunking’ of it, and (whether they are ultimately right or not) will have the knowledge and resources to make pretty impressive case. In his lifetime, Gould courted controversy, and was very well able to defend himself, but he is now no longer around to do so.
It ought to be noted that the article to which the comment quoted in the OP is a response, although it does not mention Gould or draw directly on his work, is in fact very much supportive of Gould’s general point of view about IQ and its heritability, and, in fact, supports it with new evidence and arguments. The very existence of the article is thus evidence that Gould’s position still finds support amongst relevantly knowledgeable people. The commenter quoted in the OP seems to me to be indulging in the sort of “big lie” technique that seems to be fashionable now on the political right*: instead of providing a point by point rebuttal of some widely accepted view that you disagree with, or even pointing out (what may be true) that there is some controversy about it, you simply announce that it has been discredited (meaning, actually, that it has been strongly criticized by at least one person, whose conclusions you like), and hope that your readers will just take your word for it.
*More often you find it in economic discussions, sometimes even on these boards, where people will just flatly declare, for instance, that Keynes’ theories have been entirely refuted, or that FDR’s policies are now known to have prolonged the great depression, rather than shortened it. There have certainly been arguments made for both of those claims, but it is flat out false (not to say dishonest) to imply that they are the established consensus in the relevant expert community.njtt points out what was Gould’s “ideological” stance on matters such as IQ, education, sociobiology, etc.: staunch opposition to claims that anyone is just “born better” (he had the 1996 reissue of* The Mismeasure of Man* presented as a refutation to The Bell Curve, which I felt was not entirely right). This may or may not have been influenced by his own family immigrant roots and having a developmentally challenged son: In his more opinionated essays you can clearly read strong discomfort at that in the real world, arguments that some people are “born better” too damn often are followed by “therefore there’s no point in doing anything to aid those who were not”.
Again, the mindful reader should apply the same standard to Gould as he did to the earlier studies and look for underlying bias. The thing is that for some critics, there is no such thing as “underlying bias coloring how you read the results”, there can only be deliberate misrepresentation. Because of course these critics themselves can divest into a state of total objectivity when THEY write…
One does wonder to what extent Gould’s and for that matter Sagan’s (or Kaku’s, or Feynman’s, or Dawkins’, or Hawking’s or you name him/her…) positions on non-hard-science issues may be conveniently used to harm their hard-science rep, and OTOH to what extent is it their own, or is it the lay press’ and the publishing machine’s fault, that they’re projected as having wisdom as Philosophers because they excel at their specialized research fields.
Richard Dawkins’ prominent praise on the jacket of Wonderful Life (“Unputdownable!”) is taken from a review which begins “If only Stephen J. Gould could think as clearly as he writes!” 
I’ll select Gould over Dawkins every time when I’m looking for something to read, though.
Sometimes I judge a man by the enemies he makes. In this case, I’ll take Gould over Dennett all day and all night. He wasn’t perfect, by any means and he probably went too far in the Mismeasure book, but I think he was important.
The trouble with drawing inferences from twin studies is that they share a lot more than heredity. The came out of the same womb and, usually, had the same upbringing. If they were separated at birth, they still may have been raised in similar circumstances, at least more similar that two people chosen at random.
Anyway, the business of being able to quantify the importance of nature vs nurture. It may well depend entirely on the environment.