In behavioral genetics and epidemiology, the "Gloomy Prospect" refers to the notion that non-shared environmental influences are unsystematic, idiosyncratic, serendipitous events.
It is generally used to describe the messy and individualized tiny and innumerable, but causal environmental effects.
They explain that, "One gloomy prospect is that the salient environment might be unsystematic, idiosyncratic, or serendipitous events such as accidents, illnesses, and other traumas, as biographies often attest...
It is possible that nonshared environmental influences could be unsystematic in the sense of stochastic events that, when compounded over time, make children in the same family different in unpredictable ways"[2] Turkheimer and Waldron (2000) conducted a meta-analysis on the influx of new literature inspired by Plomin and Daniels (1987) regarding the systematic effects of environmental differences within families.
"[5] Smith (2011) brings the gloomy prospect with epidemiology as an underlying mechanism of chance events.