The different forms of a gene that determine a specific characteristic are called alleles.

Here's a breakdown:

* Gene: A segment of DNA that codes for a specific protein, which in turn influences a particular trait.

* Allele: A variation of a gene. For example, the gene for eye color might have an allele for blue eyes and an allele for brown eyes.

* Trait: A characteristic or feature of an organism, such as eye color, height, or hair color.

Each individual inherits two alleles for each gene, one from each parent. These alleles can be the same (homozygous) or different (heterozygous), and they determine the expression of the trait.

Let me know if you'd like to explore the concepts of homozygous, heterozygous, dominant, and recessive alleles in more detail!