Investigation of the public's understanding of genetic terms and concepts is an essential component in the design of effective communication strategies for genetic and genomic information. Research has begun to clarify individuals’ perceptions, beliefs and factors that influence understanding [9
]. Although this research has not been framed in terms of health literacy to date, existing findings can still shed light on levels of background conceptual knowledge about genetics and genomics in the general public and across some population subgroups. This section summarizes major themes in this body of literature and highlights gaps to be addressed in future studies.
In the 1990s, a major theme in the research into the public understanding of the role of genes was exploration of beliefs about causes of birth defects and genetic conditions. For example, Cohen et al. [10
] found variability in these beliefs across racial and ethnic groups, with a significant difference in attribution of birth defects to chromosomal causes. They also observed some differences in beliefs based on whether or not the participant had a family history of a birth defect. Although 43% of participants in this study had no more than a high school degree, differences in beliefs based on educational attainment were not examined. In another study in this area, Lafayette et al. [11
] found that most relatives of individuals with cystic fibrosis underestimated their carrier risk and overestimated their risk of having a child with the disease. These researchers found that individuals with lower educational attainment had less knowledge about cystic fibrosis. A qualitative study suggested that adults who had genetic counseling and carrier testing had fairly high knowledge about cystic fibrosis, although the socio-demographic characteristics of the participants were not reported [12
]. These findings therefore suggested significant differences across groups in understanding of the role of genes in conditions such as birth defects as well as a potential correlation between education and knowledge about genes.
In more recent public understanding research, studies have focused both on individuals’ beliefs about genetic causation for common, complex health conditions and on their understanding of basic genomic concepts. Parrott et al. [13
] examined perceptions of the influence of various factors on human traits and common diseases, such as cancer, among 77 focus group participants. Their findings suggested that people did not give genes a primary role in the causation of all human characteristics; they believed that the relative role of genes and other factors varied for different traits. For example, the effect of genes on the causation of breast and prostate cancer was seen as greater than on lung cancer. In this diverse sample, differences in attributions were seen by race, gender, income and having had a biology course in college. Interestingly, the pattern of the results suggested that attributions were specific to different conditions and traits rather than being a global attitude about the role of genes. Other recent research has also suggested that the public generally does not believe that an individual carrying a gene variant will certainly develop an associated health condition. Based on the results of 13 focus groups, Bates et al. [14
] found that only about a quarter of participants believed that a person who had a gene for heart disease would certainly get the disease, although perceived risk was somewhat greater among African Americans compared to European Americans. Other qualitative research has probed more deeply into factors affecting this sense of perceived risk. A meta-ethnographic review of qualitative research studies found that individuals’ experiences of family members’ illnesses and personal models of disease causation influenced their perceived vulnerability. The findings suggested that differences in perceived vulnerability to various health conditions may affect how individuals respond to information about genetic risk [15
]. However, the review did not examine differences in perceived vulnerability or understanding of familial risk across population subgroups. These studies, taken together, indicate that the general public does have an understanding of the multifactorial nature of common, complex conditions. Results to date also suggest that personal experiences influence individuals’ perceived risk of disease.
In another major theme in research into the public's understanding of genetics and genomics, some studies have focused more specifically on understanding of underlying genetic concepts. In qualitative interviews with 62 adults, Lanie et al. [16
] found that participants had a limited understanding of what genes are, how they are inherited and where they are located in the body. However, participants generally believed that they understood information about genes. The authors did not report differences among subgroups, although 68% of participants had at least some college education. Mesters et al. [17
] found similar gaps in and overestimation of understanding among 69 individuals participating in focus groups. In this study, although participants talked about genes and DNA in association with cancer, their understanding of these concepts did not go deeper than word familiarity. Molster et al. [18
] examined individuals’ understanding of genetic concepts in a cross-sectional telephone survey of 1,009 adults in Western Australia. The findings showed that although most respondents were aware of basic genetic concepts and the connection between genes, inheritance and risk of disease, a significantly lower number of respondents understood the biological mechanisms underlying these connections. Respondents also had misconceptions around the meaning of increased genetic risk. Those with 12 years or more of education, those who were between 18 and 44 years of age, women, those with higher annual household incomes, and those who had sought information about genes had higher genetic knowledge. The findings of these studies therefore suggest that members of the general public have some familiarity with terms used in genetics and genomics, but substantial gaps exist in their understanding of the underlying concepts.
Smerecnik et al. [19
] have recently added to this literature by describing a framework that can arrange this line of research. The authors conducted a literature review examining current public knowledge of genetic risk factors for multifactorial diseases and found that this knowledge is limited. They proposed a theory-based framework to better understand the public's current knowledge regarding this topic. The framework distinguishes between 3 different types of knowledge of genetic risk factors, namely, awareness knowledge, how-to (practical) knowledge and principles (theoretical) knowledge. The authors describe these forms of knowledge as along a continuum, representing increasingly complex forms of knowledge. This framework therefore has the advantage of allowing researchers to examine how deeply the general public understands concepts.
One additional area within the public understanding of genetics literature has focused on possible influences on understanding, particularly the effects of the mass media. Increasing attention has been paid to new genetic discoveries and genetic tests in the media, in ways that might hype genetic discoveries or present them as threats [20
]. Although concerns have been raised that such attention to genetic discoveries might heighten beliefs among the general public of genes as a primary causal factor for common, complex conditions [21
], the findings presented above suggest that this has not generally been the case, at least for the majority of individuals. The effects of the mass media on public understanding of genetics and genomics are an important area for additional research.
In summary, research to date regarding the public's understanding of genetics and genomics suggests that individuals do believe that genes play a role in the causation of common, complex diseases. However, they do not seem to believe that genes are the primary causal factor and have a more multifactorial understanding of these diseases. While members of the general public may be familiar with genetics terms, they may have substantial knowledge gaps regarding basic facts about genes and DNA. Individuals may also overestimate their understanding of concepts related to genetics. This research base has a number of substantial limitations to date. Studies have generally been small and qualitative, potentially limiting the generalizability of findings. There is a clear need for additional large quantitative studies examining public understanding in representative population samples with sufficient sample size to examine differences across subgroups. Most notably, studies have not yet examined differences in knowledge or understanding across groups with varying levels of health literacy. These data are critical to developing approaches to communicate about genetics with adults who have limited health literacy. In addition, the impact of differences in knowledge on responses to new genetic information has not been systematically examined, as will be discussed further below.