Why The Gloomy Prospect? I lifted the phrase from Robert Plomin in 2000, in a paper linked here. Plomin and Daniels' original comment has been reproduced here.
Plomin and Daniels said:
One gloomy prospect is that the salient environment might be unsystematic, idiosyncratic, or serendipitous events such as accidents, illnesses, or other traumas . . . . Such capricious events, however, are likely to prove a dead end for research. More interesting heuristically are possible systematic sources of differences between families. (p. 8).
To which I replied:
The gloomy prospect looms larger for the genome project than is generally acknowledged. The question is not whether there are correlations to be found between individual genes and complex behavior—of course there are—but instead whether there are domains of genetic causation in which the gloomy prospect does not prevail, allowing the little bits of correlational evidence to cohere into replicable and cumulative genetic models of development. My own prediction is that such domains will prove rare indeed, and that the likelihood of discovering them will be inversely related to the complexity of the behavior under study.
I think events since 2000 have borne me out: scientific study of the nonshared environment and molecular aspects of the genome have proven much harder than anyone anticipated. But I still feel bad about harping on it, as though I am spoiling the good vibes of hardworking scientists, who are naturally optimistic about the work they are conducting. But ever since I was in graduate school, I have felt that biogenetic science has always oversold their contribution, tried to convince everyone that the next new method is going to be the one that finally turns psychology into a real natural science, drags our understanding of ourselves out of the humanistic muck. But it never actually happens. More on that next time I write.