A parent tells the nurse, "I am worried about my 13-year-old son. He hasn't started puberty, and my daughter did when she was 11 years of age. "Which would the nurse explain to the parent about puberty in boys and girls?

A. Unusual because the onset of pubescence is usually the same in siblings: The timing of puberty can vary significantly among siblings due to genetic, nutritional, and environmental factors. Siblings often enter puberty at different ages. Variation within families is considered normal. B. Unusual and requires further evaluation of the son: Puberty in boys commonly begins between 9 and 14 years of age, with testicular enlargement as the first sign. At 13 years, the absence of visible pubertal changes can still fall within normal limits. Further evaluation is typically considered only after age 14 with no pubertal development. C. Abnormal because the onset of pubescence is usually earlier in boys than it is in girls: Girls generally enter puberty earlier than boys due to earlier activation of the hypothalamic–pituitary–gonadal axis. This option reverses the expected developmental pattern. D. Normal because the onset of pubescence is usually earlier in girls than it is in boys: Girls typically begin puberty between 8 and 13 years, while boys usually begin between 9 and 14 years. It is common for girls to show pubertal changes earlier than male peers or siblings. The son’s development remains within an expected age range.