It is widely acknowledged in the literature on philosophy of biology and, more recently, among biologists themselves that the gene concept is currently in crisis. This crisis concerns the so-called "classical molecular concept", according to which a gene is a DNA segment encoding one functional product, which can be either a RNA molecule or a polypeptide. In this paper, we first describe three categories of anomalies that challenge this way of understanding genes. Then, we discuss proposals for revising the gene concept so as to accommodate the increasingly known complexity of genomic architecture and dynamics. Our intention is to provide an informative overview of recent proposals concerning how we should conceive of genes, which are probably not very familiar to many science educators and teachers, but can bring relevant contributions to genetics teaching, in particular, to a more critical treatment of genes and their role in living systems.