High heritability estimates imply what about environmental effects?

• A. They prove genetics exclusively determine traits
• B. They show no environmental influence
• C. High heritability excludes environmental influence
• D. High heritability does not rule out environmental effects

Answer: (D)

High heritability means that, in a given population and environment, most of the observed variation in a trait among individuals is due to genetic differences rather than environmental differences. This does not mean the environment has no effect. Heritability is about variance within a group, not a statement about individuals, and it can change depending on the environment and the population studied. It also allows for gene–environment interactions, where environmental conditions influence how genes are expressed. For example, height can be highly heritable, yet nutrition and overall health can substantially affect how tall people actually become. So, a high heritability indicates genetics accounts for a large part of the variation in that context, but environmental effects can still be present and influential.