Traits acquired during an organism's lifetime through use or disuse can be passed on to offspring. If an animal develops strong muscles through use, its offspring inherit those strong muscles.
Lamarck's theory of inheritance of acquired characteristics was disproven by Darwin's mechanism of natural selection and later by Mendelian genetics. Modern genetics shows inheritance works through genes, not acquired traits. However, epigenetics has revealed that some environmental factors can affect gene expression in ways that are heritable, adding nuance to the traditional view.
Reception
Sources
- Nature: Epigenetics and Lamarckism PRIMARY
- Stanford Encyclopedia: Lamarck REFERENCE