Have you ever met a friend's parents, and realized that your friend was basically a mini-me of their mom? Not just because they both have brown hair or a pointy nose. It's how they talk, the way they both like making silly puns, their attitudes and beliefs.

Now, the question is, how much of that similarity is genetic, and how much is just a function of the fact that your friend grew up with their mom, and pretty much learned how to be a human being by watching her? This is the age old question: nature or nurture?

Nature is the part of human behavior that's biologically determined and instinctive. When a baby latches onto your finger and won't let go and it's basically the cutest thing in the whole world, it's not because they learned to do that. It's natural.

A lot of human behavior, however, isn't instinctive. It comes, instead, from how you're nurtured. The nurture part of behavior is based on the people and environment you're raised in. And it's this second part, the social environment that determines human behavior, that sociologists tend to investigate and have many different theories about.

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To a big extent, we develop our personalities and learn about our society and culture through a social process; one known as socialization. Sounds legit, right? But what happens if you don't have people around you? Social isolation affects our emotional and cognitive development a lot.

To get a glimpse into how and why this is, let's go to the thought bubble to look at sociologist Kingsley Davis' case studies on Anna. In the winter of 1938, a social worker investigated a report of child neglect on a small Pensylvania farm, and found, hidden in a storage shed, a five-year-old girl.

That five-year-old girl was Anna. She was unwanted by the family she was born into, and was passed from house to house among neighbors and strangers for the first six months of her life. Eventually, she ended up being kept in a shed with no human contact other than to receive food.

Kinglsey Davis observed Anna for years after her rescue, and wrote about the effects of this upbringing on her development. When Anna was first rescued, she was unable to speak or smile, and was completely unresponsive to human interaction. Even after years of education and medical attention, her mental development at age 8 was less than that of a typical two-year-old.

This is a story with both a sad beginning and a sad ending. Anna died of a blood disorder at the age of 10, and Davis' study of how isolation affects young children was only one of many that have shown how a lack of socialization affects children's ability to develop language skills, social skills, and emotional stability.

Thanks, thought bubble. There are lots of different theories about how we develop personalities, cognitive skills, and moral behavior, many of which come from our siblings in social science, psychologists.

Take Sigmund Freud. You've heard of him. Austrain guy. Liked cigars. Invented the field of psychoanalysis. One of his main theories was about how personalities develop. He thought we were born with something called an id.

You can think of the id as your most basic, unconscious drive. A desire for food, comfort, attention. All a baby knows is that it wants that, and it will scream until it gets it.

But then, we develop the ego and super-ego to balance the id. Ego is the voice of reason, your conscious efforts to reign in the pleasure-seeking id. Your super-ego is made up of the cultural values and norms that you internalize and use to guide your decisions. So if the id is the devil on your shoulder, the super-ego is the angel on the other shoulder, and the ego is the mediator who intervenes when the angel and devil start fighting.

Now, a lot of Freud's work hasn't stood the test of time, but his theories on how society affects our development has influenced pretty much everyone who has researched the human personality. This includes Swiss psychologist Jean Piaget, who spent much of his career in the early 1900's studying cognitive development.

While researching ways to measure children's intelligence, Piaget noticed that kids of similar ages tended to make similar mistakes. And this, to Piaget, suggested that there were four different stages of cognitive development.

First stage: touch everything. Babies learn about the world by grabbing things and sticking them in their mouths. This curious, slobbery interaction with the world is what Piaget called the sensorimotor stage: the level of development where all knowledge is based on what you can perceive with your senses.

Around age 2, a child enters the next stage, known as the preoperational stage. At this point, kids have learned to use language and begin to ask questions to learn about the world, rather than just grabbing stuff. Now they can think about the world and use their imaginations - which leads to playing pretend and an understand of symbols.

But thinking about the world is pretty much limited to how they think about the world. Kids in the preoperational stage are pretty ego-centric. If they love playing with trains and you ask them what their dad's favorite thing to do is, they'll probably say that he loves playing with trains too.

It's not until they reach the concrete operational stage, around 6 or 7, that they develop the ability to take in other people's perspectives, and begin to make cause-and-effect connections between events in their surroundings. And in the formal operational stage, at about 12, Piaget said kids begin to think in the abstract and use logic and critical thinking.

Now, American psychologist Lawrence Kohlberg later expanded on Piaget's model of cognitive development to incorporate stages of moral development. Essentially, kids' sense of what is right begins in what Kohlberg called the pre-conventional stage, where right is just what feels good to them personally.

Next, they move to the conventional stage, where what's right is what society and the people around them tells them is right. And then, finally, children end up in the post-conventional stage, where they begin to consider more abstract ethical concepts than just right or wrong.

So, at a young age, a child doesn't realize that grabbing the candy bar they want at the store is wrong - they just want it. But then, a combination of societal norms and being scolded by their parents convinces them that stealing is wrong, no matter how much they want the candy bar. And over time, they learn that morals have gray areas; stealing is wrong if it's just for fun, but might be considered less wrong if you are stealing to feed your family.

Eventually, children reach a point where they're able to think about things like freedom and justice, and realize that societal norms about what's right may not always line up with these principles. Sure, laws against stealing candy may be just, but what about laws that say only certain people can get married? Just because something is a law, is it right?

How you feel about that question may depend on your socialization. And on your gender. Carol Gilligan, an American psychologist who started out as a research assistant and collaborator of Kohlberg's, explored how girls and boys experience these stages differently. She realized that Kohlberg's original studies only had male subjects - which may have biased his findings.

When she expanded the research to look at both male and female children, she found that boys tend to emphasize formal rules to define right and wrong - what she called a justice perspective. Whereas, girls tended to emphasize the role of interpersonal reasoning in moral decisions - what she called a care and responsibility perspective.

Gilligan argued that these differences stem from cultural conditioning that girls receive to fulfill ideals of femininity. She thought that we socialize girls to be more nurturing and empathetic, and that influences their moral interpretation of behavior.

The next theory of social development I want to focus on is from American sociologist George Herbert Mead, who was one of the founders of the sociological paradigm we talked about a few episodes ago, known as symbolic interactionism.

His work focused on how we develop a "self." What makes up the you that is inherently you? Are you born with some inherent spark of you-ness? According to Mead, no. Instead, he believed that we figure out who we are through other people. All social interactions require you to see yourself as someone else might see you - something Mead described as "taking on the role of others." 

In the first stage of development, according to Mead's model, we learn through imitation - we watch how others behave and try to behave like them. You see your mom smile at your neighbor, so you smile too. And Mead observed that as kids got older, they moved on to a new stage - play.

Rather than just imitating your mom, you might play at being a mom, taking care of a doll. Assuming the role of "mommy" or "daddy" is a kid imagining the world from their parent's perspective.

The next stage of development is the game stage, where children learn to take on multiple roles in a single situation. What does that have to do with games? Well, games use rules and norms, and require kids to take on a role themselves, and develop that role in reaction to the roles that others take on. 

Team sports are a great example of this. When you're playing soccer, you need to not only know what you're going to do, but also what your teammates and your opponents will do. If you were ever the kid who ended up running the wrong way on the soccer field because you didn't realize the ball had switched possession, you know how important it is to anticipate what other people do.

The last stage, in Mead's model, occurs when we learn how to take on multiple roles in multiple situations. In this phase, we weigh our self and our actions not against one specific role, but against a 'generalized other' - basically a manifestation of all of our culture's norms and expectations.

Now, you might have noticed that all these theories focus on childhood. So, does that mean that your personality is set once you hit 18? No. Definitely no. As anyone over 18 will tell you, you keep growing well past high school.

And that's why yet another theorist, German-born psychologist Erik Erikson, came uo with his own eight-stage theory of development, that goes all the way from infancy to old age. He based these stages on the key life challenge of each period of life. When you're a toddler, for example, your biggest challenge is getting what you want - or as Erikson puts it, gaining autonomy, which helps you build skills and confidence in your abilities.

But once you're a young adult, you've got plenty of autonomy. Now, a bigger challenge is developing intimate relationships. Falling in love, finding friends - there's a reason that's the focus of every 20-something sitcom. And his list goes on.

Every life stage from when you're born to when you die features different expectations that inform what we see as markers of social development. Moving out, getting married, having kids - they're all societal markers of social development as an adult. But whether you feel like one or not, adulthood will come for us all - and it's your socialization that will determine how exactly you perform the role of "adult."

Next week, we'll talk about the different agents of socialization that shape who we really end up being. Today we learned about social development, starting with the role of nature and nurture in influencing a person's development. We talked about social isolation and the importance of care and human interaction in early years for proper emotional and mental development.

Then, we talked about five theories of development: Freud's id, ego, and super-ego; Piaget's Four Stages of Cognitive Development; Kohlberg and Gilligan's theories of moral development; Mead's theory of self; and Erik Erikson's life stage theory.

Crash Course Sociology is filmed in the Dr. Cheryl C. Kinney Studio in Missoula, MT, and it's made with the help of all of these nice people. Our animation team is Thought Cafe, and Crash Course is made with Adobe Creative Cloud.

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