Here's why:

* Homologous chromosomes are a pair of chromosomes that have the same genes in the same order, but the alleles (versions) of those genes may differ. This means they code for the same traits, but potentially different expressions of those traits.

* Alleles are alternative forms of a gene. For example, one allele for eye color might code for brown eyes, while another allele codes for blue eyes.

So, while homologous chromosomes share the same genes, they might carry different versions of those genes, leading to variations in traits.