According to some studies :
People born later in the year (mainly after September) will have less success in their adult/teenager life.
The theory states that since they enter into school at the same time Janurary-born children do, they have had less time to develop (since we develop so fast as children, a few months makes a lot of difference). Early-month born are usually picked first for sport teams and excel in most activities such as writing, math and science (since their brains are further developed). This leads to poor self-esteem for the later-month born and in-turn lead them to be less successful in their adult lives.
Thought? ~
