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.
Girls may enter puberty at seven, but will experience a majority of their growth in height when they are around 10.5 years old. Boys may begin puberty at the age of eight, but experience growth when they are around 13 years old. Since girls enter puberty before boys, they also experience growth spurts early. This can result in girls towering over boys of the same age. On an average, boys grow the fastest between the ages of 14 and 15.