Chapter 17: Breast’s and regional lymphatics Cultural competence • Timing of puberty is influenced by genetic and environmental factors • Research data indicate age differences in onset of puberty according to different ethnic groups. • Obesity contributes to the early onset of puberty. • Menses began at an average age of 12-16 years for African-American girls and age 13 for white girls. Cultural competence: Breast cancer I, II, III • Incidence of breast cancer varies in ...