One of the principles of development is that happiness varies at different periods in the development pattern. According to this principle
1
The first year of life is usually the happiest period.
2
The Puberty is the happiest period of life and the first year is also the happiest period of life.
3
The Puberty is the most unhappy period of life.
4
The first year of life is the happiest, and the Puberty is the most unhappy period of life.