Children don't develop in a vacuum. Unless you plan on keeping your little one in a bubble until she is ready to head off to college, there are many different external factors that will influence how she grows, learns and changes. While these can vary from the totally tiny to the most major, there's no doubt that almost anything, from friends to the media, can have an impact on development.
As your child ventures out into the social world, he's sure to meet the influences of peer pressure. That's not to say that peer pressure at the preschool or toddler age is the same as what a high-schooler would see (it's extremely unlikely that the other 4-year-olds are going to push your preschooler to drink a beer), but the influence of like-aged friends is a real factor. If little Johnny sees that Jeremy can't get enough of playing with toy trains, it's likely that he'll want to try them out too. It's not uncommon for preschool-aged kids to influence each other's likes, dislikes and choice of activities. Additionally, interactions with other children can quickly shape your child's critical-thinking skills and problem-solving abilities. Group activities such as tag and hide-and-seek often mean that children must negotiate others' behaviors and learn how to adjust.
You and your family are first and foremost in shaping your child's development. While friends and other non-family members certainly have a swaying impact, the immediate family is typically the most influential interpersonal factor when it comes to kids. Your child's behaviors, what he finds acceptable and not acceptable, likes and dislikes and norms, all come from the family. For example, if talking during mealtimes is a staple of a family's behavior, the child will most likely act like a little chatterbox in almost every eating situation.
A study by the Henry J. Kaiser Family Foundation found that kids under the age of six spend an average of two hours a day staring at screens, so media sources such as TV, DVDs and the Internet can be expected to have a major influence in most young children's lives. While your little one probably isn't spending the majority of her day watching some sort of media device, even a two-hour-long stretch can impact her development. Time spent passively watching programs takes away from true play. Sitting in front of a screen instead of running free and exploring everything from the tree in the backyard to the bevy of dolls that you bought for her means that your child isn't making the most out of opportunities to develop physical, social, emotional and cognitive skills.
Your little learner isn't quite college-bound yet, but she can still benefit from a quality education. While there is no requirement for toddlers and preschool-aged children to go to any type of formal educational institution, providing a "school" environment can influence development on many different levels. According to the American Academy of Pediatrics, early education can actually increase a young child's healthy development. Whether your tot goes to a preschool, day care, early learning center or any other type of educational program, she will have the chance to learn things that she might not get to at home, while spurring her social and emotional growth by playing, sharing and taking turns with other children.