External factors have far-reaching affects on your child's development. Your child's home environment, the friends with whom he spends time, the food that he eats and the amount of screen time -- not to mention the content -- are factors that influence his physical, social and cognitive development in powerful positive and negative ways.
According to the World Health Organization, early childhood is the most intensive time of brain development in a person's life. In the first three years of life, a child's brain is most sensitive to external factors -- including family environment. A child whose family does not provide an enriching and stimulating environment -- whose parents don't interact and speak to him and don't nurture a healthy attachment -- may become developmentally behind. WHO warns that a child with a stressful family environment may go on to experience learning disabilities and has a higher risk of coming down with a stress-related illness.
According to Education.com, by the time a child reaches the age of 3, he has formed friendships that begin to influence his behavior and social development. Friendships help children learn to resolve conflict, cooperate effectively and negotiate relationships. Peers influence a child's values, decisions, likes and dislikes. Peer influences can be healthy and acceptable but can also have negative effects if a child develops unwavering obedience to his peers.
Nutrition plays an important part of your child's physical and mental development, according to the American Academy of Pediatrics on the website, HealthyChildren.org. Calcium is needed to develop healthy bones and teeth, and protein and fats are necessary to give your child energy and help him grow. The AAP warns that once children start attending school and have more choices in what they eat for lunch in the cafeteria, they may stock up on sugary sodas, candy bars and chips rather than a well-balanced meal with the nutrients their growing bodies need.
A 2003 study by the Kaiser Family Foundation found that children spend an average of two hours a day in front of the screen. According to child development experts at the Kids Health website, television in moderation for children age 2 and up can be educational, but too much television can have negative affects. Children who regularly watch more than four hours of television each day have an increased risk of being overweight, and children who view violent television shows have a tendency toward aggressive behavior.