Final answer:
A family record that shows how a trait is inherited across generations is called a pedigree. It allows for the analysis of inheritance patterns and can help in predicting the likelihood of inheriting genetic disorders.
Step-by-step explanation:
A family record that indicates the occurrence of a trait is known as a pedigree. A pedigree is a diagram that traces the inheritance of a trait through several generations within a family. This tool can be incredibly useful in genetic counseling and helps to predict the likelihood that offspring will inherit a genetic disorder, by showing whether the trait is sex-linked, autosomal, dominant or recessive. By analyzing a pedigree, one can also determine if individuals with a particular trait are heterozygous, carrying two different alleles, or homozygous, carrying two identical alleles.
In the process of pedigree analysis, individuals who exhibit a certain trait are often indicated with a particular mark or color. For example, in a given pedigree, those with a genetic disorder might be shown in blue and could have the genotype aa, while unaffected individuals are indicated in yellow. Such visual cues help indicate how traits are passed down through the generations and can help predict an individual's risk of inheriting certain heritable genetic disorders.