Emma and Anna are identical twins who were adopted by different families a few weeks after birth. Although genetically identical, they grew up with different physical and psychological characteristics. For example, though both inherited a tendency to grow large, Anna was slim and athletic due to the active lifestyle practiced in her adoptive family. This variability can be explained by how:

for each genotype, a range of phenotypes can be expressed

Explanation:

The genetic makeup of an organism is referred to as the genotype of the organism and is responsible for determining the characteristics of an organism. The phenotype of the organism is the traits that are possessed by the organism by the expression of their genes however the phenotype of the organism is influenced by many factors. The various factors that influence the phenotype of the organism are:

1. Genotype

2. The environment that the organism lives in.

3. Stochastic developmental events

Therefore, even though Emma and Anna were identical twins having the same genotype they had variability in their phenotypes because environmental and developmental events also influence the phenotype of the organism.