CP Biology – Inheritance Practice Test

The main idea is that the environment can shape how a polygenic trait is expressed by influencing how genes are turned on or off during development. Polygenic traits come from many genes that each contribute a small amount to the final phenotype, so the overall outcome depends on how strongly and when those genes are expressed. Environmental factors—nutrition, climate, hormones, stress, exposure to toxins—can change gene expression patterns through signaling pathways or epigenetic marks. This means two individuals with similar or even identical genetic backgrounds can end up with different phenotypes because their environments altered the regulation of those many contributing genes. For example, good nutrition during growth can maximize height potential, while other environmental inputs can modify body composition, metabolism, or other polygenic traits. Importantly, the environment shapes phenotype without changing the underlying DNA sequence, which is why environments influence phenotype but do not change genotype.