People who can't follow a movie when someone else is talking can blame their genes. The ability--or inability--to listen to more than one thing at once is largely inherited, according to a study of twins. The finding could help scientists better understand disorders that involve problems in auditory processing. ... "This is the first study to show that [normal] people vary widely in their ability to process what they hear, and these differences are due largely to heredity," NIDCD director James Battey said in a statement. That's important, says Deborah Moncrieff, an audiologist at the University of Connecticut, Storrs, because skeptics had questioned attributing difficulties in listening, learning, and reading to problems in the auditory pathway. Moncrieff has developed a method for training children to strengthen the transmission of signals from the ear to the speech center of the brain
To some extent, this reminds me of face blindness, or variations in taste sensitivity within families. There is an a priori assumption that other human beings are a reflection of ourselves, so it sometimes "surprises" us that people are different from each other. The existence of cryptic heritable variation in behavior and subtle sensory differences are, I suspect, going to be one of the "big stories" in human biology in the near future. Consider for example that not only is color blindness more prevalent in males (because of sex-linked effects), but a large proportion of women have a more fine grained and diverse set of colors which they perceive because of their genetic inheritance. Not only might this explain the inability of some men to "get it" in the eyes of their partners when it comes to good taste in tone and tint, but offers the possibility, often discussed in philosophy, that humans might perceive the world of similar names very differently indeed. We all understand that autistic people "can't help themselves." Whereas in the recent past Freudian explanations put the onus on familial environment, especially the mother-child relationship, today the assumption is that autism derives in large part from a biological propensity. The taste research which I alluded to above suggests that mothers who are relatively taste insensitive vis-a-vis their children often perceive their children to be particularly picky and unreasonable eaters. The assumption is of course that humans experience the same sensory experience when the inputs are the same. Obviously in the case of taste that isn't necessarily so. Complicated this picture is the reality that many of these subtle traits exhibit a great deal of variation due to non-genetic factors, and, individuals who are deviated from the norm can develop compensating strategies which result in the masking of their deficits. A clearer and more precise understanding of the genetic and more broadly biological underpinnings of cognitive and behavioral phenomena is not conceding to determinism, rather, it is simply adding more variables in completing a map of the causal factors which shape an individual human's nature.