Which idea did lamarck propose that was rejected by his fellow sicentits?

Lamarck proposed the idea of inheritance of acquired characteristics, suggesting that traits acquired during an organism's lifetime could be passed on to its offspring. For example, he believed that if an organism developed a characteristic through use or disuse, such as a giraffe stretching its neck to reach higher leaves, that trait would be inherited by its offspring. This concept was largely rejected by fellow scientists, as it contradicted the emerging understanding of genetics and natural selection, particularly as formulated by Darwin. Instead, it was established that genetic traits are inherited through genes, not through acquired characteristics.