The same gene can play a key role in quite a variety of developmental events. The important story is that the search for genes that control development has shown us that our initial idea that genes control processes within an organism is wrong. Instead genes are one set of actors within a developmental system. The system itself contains all of the pre-existing contents of the cell, organ or organism. From before the turn of the century embryologists debated whether the cytoplasm controlled the nucleus or vice versa.
Genes are but one of many crucial components of the process.