Answer to Question 1
Answer: Personality is developing and changing the most during childhood and becomes the most stable when people are in their 40s and 50s. The most notable exception is agreeableness, which increases more after age 50.
Answer to Question 2
Answer: The teen years bring many changes as children go through puberty and, physically at least, begin to resemble adults. Personality changes but not all that much. Studies have found that both boys' and girls' openness to experience increases between ages 11 and 18. Many teens play around with intellectual ideasthey debate politics with their friends, explore ideas about religion, and grapple with philosophical questions.