Many human traits are heritable.
Some examples include height, breast cancer, Alzheimer's disease, and cholesterol levels. To determine whether or not a given trait is heritable, investigators must collect trait data on biological relatives. Although an analysis of trait data alone may provide evidence for heritability, it will not tell us which specific genes determine the trait of interest. Fortunately, modern biotechnology allows for the collection of genetic data, which can be used to look for trait genes. Investigations that look for associations between genetic loci and traits are called genetic linkage studies.