Final answer:
The most likely mode of inheritance is autosomal dominant. The genotype of I-1 is aa and the genotype of II-3 is AA.
Step-by-step explanation:
The most likely mode of inheritance can be determined by analyzing the pedigree chart and identifying any patterns of inheritance. In this case, we can see that the trait is expressed in every generation, which suggests an autosomal dominant inheritance pattern. This means that a single copy of the gene is enough to express the trait.
The genotype of individual I-1 can be determined by looking at the pedigree. Since individual I-1 does not have the trait, we can conclude that their genotype is homozygous recessive (aa).
The genotype of individual II-3 can also be determined using the pedigree. Since this individual expresses the trait, we can conclude that their genotype is homozygous dominant (AA).