This question is incomplete. Here's the complete question.
Regarding the changes that people go through during puberty:
If you were not able to experience the above-listed changes, what might have caused such difference?
Answer: It´s probably due to a hormone disbalance or the delay of my puberty.
Explanation:
Normally, puberty begins between 8 and 13 years old for girls and 9 and between 15 years old for boys. However, every body is different, and there are many chances that puberty starts outside of those age ranges. Nevertheless, if that happens it´s recommendable to visit a doctor, just in case.