Which of the following describes a recessive gene?

A recessive gene is characterized by being masked or hidden when a dominant gene is present. This means that an individual must inherit two copies of the recessive gene, one from each parent, for its trait to be expressed in their phenotype. When only one dominant gene is present, it will override the effect of the recessive gene, making the recessive trait not observable in that individual.

The other choices do not accurately describe the nature of recessive genes. For instance, while it is true that a recessive gene is expressed only in the presence of two identical alleles, the inclusion of the term "identical" in that definition aligns with the reality that recessive genes require homozygosity to be expressed, but it doesn't fully illustrate the masking aspect. Additionally, dominant genes, as stated in another choice, take precedence over recessive genes, which reinforces the concept but doesn't define the recessive gene itself. Finally, the assertion that a recessive gene "only affects male offspring" is incorrect, as recessive genes can affect individuals regardless of gender when appropriately inherited.