The closer together two genes are on a chromosome, the less likely their alleles will be separated by crossing-over.

This statement reflects a fundamental concept in genetics regarding the linkage of genes on chromosomes. When two genes are located close to one another on the same chromosome, they are said to be linked. The proximity means that during the process of meiosis, when chromosomes are exchanged between homologous pairs, the likelihood of crossing-over occurring between these closely situated genes is reduced.

Crossing-over is a mechanism that increases genetic diversity by allowing exchange of genetic material between homologous chromosomes. If genes are far apart on the chromosome, the chance that they will be separated during crossing-over increases, leading to a higher likelihood of the alleles being shuffled. Conversely, tightly linked genes tend to be inherited together. This principle is critical for understanding inheritance patterns and is utilized in genetic mapping to locate genes associated with specific traits.

In summary, the closer two genes are on a chromosome, the less likely it is for their alleles to be separated during crossing-over, resulting in them being inherited together more frequently.