Genetic variants are differences in the DNA sequence among individuals. These variations can occur in a single nucleotide, which is the basic building block of DNA, or in larger segments of DNA. Some genetic variants are harmless, while others can influence traits, such as eye color or height, and may even contribute to the risk of certain diseases. Scientists study genetic variants to understand how they affect health and development. For example, researchers might look at variants in the BRCA1 gene, which is linked to an increased risk of breast cancer. By identifying these variants, they can help develop personalized treatments and preventive measures.