Julio's Parents and Older Brothers Are Very Tall Individuals,so Everyone

Julio's parents and older brothers are very tall individuals,so everyone assumed that Julio would also be very tall once he hit puberty.However,this was not the case,as Julio is about six inches shorter than both of his siblings.Julio was diagnosed with leukemia during infancy and had to endure several cancer treatments.Even though he went into remission,doctors were concerned that his development may have been affected as a result.According to epigenetics,the most likely reason why Julio is shorter than his siblings is because

A) Julio has a different genotype than his brothers.
B) Julio's grandparents on his father's side were short in stature.
C) as the younger brother,Julio grew up in a different environment than his brothers.
D) Julio's exposure to cancer treatment may have altered his gene expression.