How can environmental factors change genes without supporting Lamarckism?

Environmental factors can influence genetic material and gene expression through mechanisms distinct from Lamarckism—the discredited theory that physical changes acquired during an organism's lifetime are directly inherited by offspring.12

Instead, environmental factors interact with genes through the following processes:

• Genetic Mutation: External agents such as radiation, drugs, and chemicals can cause physical damage to DNA. These mutations are random alterations in the genetic code rather than adaptive responses to an organism's needs or efforts, as Lamarckism suggests.31
• Epigenetic Regulation: Epigenetics involves molecular mechanisms that turn specific genes on or off without changing the underlying DNA sequence. While the environment influences which genes are activated—such as maternal behavior affecting gene activity in newborns—this is a regulatory process rather than the inheritance of acquired physical traits.4
• Gene-Environment Interaction: An organism's traits are the result of a constant interplay between heredity and environment. For example, while genes may dictate the potential for height, environmental factors like nutrition determine whether that potential is fully realized. This does not imply that the physical result of that environment is encoded into the germline for future generations.52