True or False: A dominant trait can show incomplete penetrance in a pedigree.

A dominant trait can indeed exhibit incomplete penetrance in a pedigree, making the statement true. In genetics, penetrance refers to the proportion of individuals carrying a particular genotype that expresses the associated phenotype. Incomplete penetrance occurs when not all individuals with a dominant allele express the dominant trait.

For example, an individual may inherit a dominant allele for a trait, such as polydactyly (having more than five fingers). However, if they do not express this trait, they demonstrate incomplete penetrance. This means that while the allele is present, the phenotype does not manifest in every case. Reasons for incomplete penetrance may include gene-environment interactions, epigenetic factors, or the influence of other genes.

This phenomenon is particularly important in understanding the variability of trait expression within families and across generations in a pedigree analysis. It highlights that genetic expression does not always align perfectly with inheritance patterns outlined by Mendelian genetics.