Reduced penetrance and variable expressivity are factors that influence the effects of particular genetic changes. These factors usually affect disorders that have an autosomal dominant pattern of inheritance, although they are occasionally seen in disorders with an autosomal recessive inheritance pattern.enetrance refers to the proportion of people with a particular genetic change (such as a mutation in a specific gene) who exhibit signs and symptoms of a genetic disorder. If some people with the mutation do not develop features of the disorder, the condition is said to have reduced (or incomplete) penetrance.
Although men have more muscle mass than women, both sexes reach their physical peak as young adults or anywhere from their late 20's to early 30's, according to âHuman Development: A Life-Span Viewâ by Robert Kail and John Cavanaugh.
Average Age Of Growth Spurts In Boys. The average age at which puberty begins in boys is 11 to 12 years. The end of puberty is not clearly delineated and may vary with the physical, emotional, mental, social and cultural criteria to define an adult boy. However, it usually gets complete at around the age of 17 to 18.