Final answer:
Pedigrees are used because controlled experiments like test crosses are unethical and impractical in humans. They help determine the likelihood of inheriting genetic disorders through an analysis of inheritance patterns over generations, even though predictions are probabilities rather than exact outcomes.
Step-by-step explanation:
Pedigrees are used in the analysis of human genetic disorders because unlike in controlled experiments with plants like Mendel's peas, it is unethical and impractical to perform test crosses in humans. A pedigree is a valuable tool that outlines the inheritance patterns of genetic traits and disorders across multiple generations. This helps determine the likelihood of offspring inheriting certain conditions, particularly when considering recessive genetic disorders.
With over a century of genetics studies and the sequencing of the human genome, scientists better understand the expression of an individual's genotype as their phenotype. This knowledge is crucial for medical professionals to estimate the risk of heritable genetic disorders. However, many diseases exhibit complex inheritance patterns or are influenced by environmental factors, making predictions based solely on parental genotypes or phenotypes challenging.
When considering specific single-gene disorders, such as albinism, cystic fibrosis, and Huntington's disease, pedigree analysis, informed by Mendelian inheritance patterns, becomes essential for estimating the genetic risks for offspring. Due to the impact of chance and the typically small size of human families, predictions made using pedigree analysis are estimated probabilities rather than exact outcomes.