This international study examined data from sibling groups, including 1800 volunteers from ORCADES and the Viking Health Study - Shetland. An international group of 100 researchers studied 178,076 siblings to assess the impact of their genetics and environment on their health and social lives. They found that the genetics of many social traits - such as education level, age when first gave birth, smoking and depression - were strongly influenced by family environment or social effects, such as more frequent marriages between similar individuals. In contrast, the genetics of biological traits - such as poor cholesterol levels and body mass index (the ratio of body weight to height) - were found to be less likely to be influenced by these effects. The researchers examined genetic, educational and health data on siblings from 19 studies on four continents. The study included data from 1,811 of volunteers who participated in ORCADES and the Viking Health Study - Shetland and had a brother or sister in the study. Generation Scotland was involved in this study and is currently recruiting new study participants. Image Genome-wide association study (GWAS) applied in this study A research method known as the Genome-Wide Association Study (GWAS) was applied to the sibling data. It was used to determine any genetic associations between health conditions and millions of common genetic variants. Genome-wide association studies typically use samples of unrelated individuals. However, in this new study, siblings were used to estimate genetic effects. The pieces of DNA passed from parents to siblings are completely random. So if the siblings who pass them on have more similar trait values, researchers can be more confident that this set of genes directly affects the trait - because the siblings share the same family and social environment. This is not the case in studies of unrelated individuals, where those who have more children or are more likely to smoke may share factors other than genetics. Our findings suggest large-scale family datasets provide new opportunities to quantify direct effects of genetic variation on human traits and diseases. Looking at sociological questions and genetics together is a powerful tool for understanding why different health and social outcomes happen, providing better insight for potential interventions and treatments. Dr Laurence Howe, Lead Author In fact, the team showed that previously reported GWAS associations - which did not focus on siblings - tend to overestimate the effects of DNA on many traits, including: Length of time in education Cognitive ability Age when first gave birth Whether someone has ever smoked Depressive symptoms Number of children In addition, they found that estimates of a number of important genetic measures-such as a trait's proportion of genes (heritability) and the proportion of genetics is shared between traits (genetic correlation)-were distorted when not calculated using estimates from siblings. The international collaboration established for this study is continuing to work together and explore these issues further, including looking at associations between trios consisting of mother, father, and offspring. Related Links Viking Genes homepage Generation Scotland Within-sibship genome-wide association analyses decrease bias in estimates of direct genetic effects This article was published on 2022-11-03
