Final answer:
Genes that are likely to be expressed in a person are those associated with dominant traits or homozygous recessive genes. Scientists study genotypes and phenotypes to predict inherited traits and the risk of genetic disorders. Pedigree analysis and understanding of X-linked traits help in understanding inheritance in humans.
Step-by-step explanation:
The genes that are likely to manifest in a person are those associated with dominant traits or in cases of recessive traits, those where the individual has two copies of the recessive gene. Through over a century of genetic studies and the sequencing of the human genome, scientists can predict some of the characteristics that offspring will inherit based on the genotypes and phenotypes of the parents.
This includes the determination of the risk for certain heritable genetic disorders. Genetic testing can be very informative for single-gene disorders, but diseases with multigenic inheritance patterns are more complex due to the interaction between multiple genes and environmental factors.
Researchers use pedigree analysis to study inheritance patterns in humans, since test crosses are not ethical. Additionally, X-linked traits, such as some forms of color blindness and hemophilia, can be understood looking at inheritance patterns, where males are more frequently affected as they inherit only one X chromosome.
Polygenic inheritance is when multiple genes contribute to a trait, as seen with characteristics like skin color and height. Understanding how genes are passed down and expressed is crucial in predicting phenotypic outcomes and identifying potential genetic risks.