One area of controversy about the human condition concerns the interactions between the largely independent concepts of innateness (vs. learned or environmentally caused) and similarity (or difference) of individuals and groups. The controversy primarily concerns differences in behavior and the mental capacities and dispositions that underlie it. This is partly because the presence of physical differences is obvious when we compare individuals, the sexes, and (to some degree) ethnic groups. Behavior is also clearly highly influenced by experience, and our cognitive abilities are uniquely important in determining our success in the human created environment that we live in.

In its simplest form, the Nature Versus Nurture dispute concerns the “individual difference” row in this table, although there is also substantial concern related to the possibility of innate group differences. See Harald Eia: Brainwash for an interesting series of videos examining the nature/nurture dispute.

When we say that something about a person is innate, we mean that it is a stable trait or inclination that was present in them even as a child. Let's take this definition literally and say a trait is innate if was caused by anything that was inside us before they were born. Our genome is clearly the primary internal cause but our development is controlled by the interaction between our genes and everything else.

It can be hard to tell whether something is innate or not (see Nature Versus Nurture):

• Prenatal causes: A trait may be present from birth, but be caused by something outside our developing body. There are known harmful influences such as drug consumption, but often it's hard to tell apart from …
• Developmental randomness: We know the detailed structure of the body (including the brain) can't be directly specified in the genome because there just isn't enough information there. Development is highly dependent on self organization to keep things on track (see Randomly growing an embryo). We don't know how big a factor this is, but it surely contributes to the non-shared environment in heritability estimates.
• Delayed appearance: Most people would accept that secondary sexual characteristics such as voice change in men and broadening of hips in women are innate differences, but they don't appear until adolescence. Humans are born quite immature, and development continues for about 20 years. In particular, we now know that significant irreversible remodeling happens in the brain at adolescence. One theory is that this consolidates experience, gaining efficiency at the cost of future flexibility (watch Sarah Jayne Blakemore on the Adolescent brain), but some of these changes, such as the development of sexual behavior, are clearly innate.

As well as these practical difficulties in determining the cause of a trait, even knowing the cause, we still might not be sure. Is developmental randomness an innate cause? But random development continues even after birth. We also can't ignore free will. As soon as we are born we begin to influence our experience by where we look and what we pay attention to. If we consistently choose to behave in certain ways, then that could develop into a stable behavioral trait, and can also affect our physical development.

What do we want “innate” to mean? Why do we care? In the context of the Nature Versus Nurture debate, much of the concern is that innate traits are hard to change. How hard are these things to change?

• Developmental randomness: can't be controlled at all.
• Genetics: we can make genetically engineered animals by starting with a single cell, and this could almost certainly be done in humans too. But even ignoring the issue of what changes (if any) would be desirable or morally acceptable, the fact is that (aside from repairing specific genetic defects), we currently have absolutely no idea of what genetic changes we would need to make to affect behavior or even to shift simple physical traits such as height.
• Transgenerational epigenetics: this information is heritable, just as with genetic information. Not much is known yet, but there is fairly convincing evidence that malnutrition can cause physiologic changes that persist across generations. This raises the possibility that improvements in the environment may take more than one generation to appear.
• Irreversible development: Our bodies (and brains) undergo successive irreversible changes during development. Malnutrition, abuse and neglect clearly have lasting effects, and learned behaviors and attitudes can also be frozen in by developmental changes.

From our individual perspective, all these things are very difficult to change, but these fades over into factors that would normally be considered environment:

• prenatal environment
• ubiquitous environmental factors
• self selected environment

Because of the fairly recent dispersal of humans out of Africa, followed by population growth, humans have a relatively low level of genetic diversity (in comparison to other species) and 85% of the existing genetic variation is present within every population, while only 8% occurs between continents. Stereotypes about sub-Saharan Africans are particularly dubious, since that subcontinent contains the greatest genetic diversity, see Human Genetic Variation.

Although humans are relatively genetically homogenous, genetic differences do underlie individual differences in talent, motivation and behavior that humans happen to consider highly important (see Behavioral Genetics). Because of the relative similarity of all human populations, we would expect the variation between geographically defined groups to be smaller than individual variation. Even small differences can be detected with confidence using the large samples available, but any behavioral differences could be explained by culture and other aspects of the local environment, so it is hard to know what component might be innate.

How can it simultaneously be true that “All people are created equal” and that “No two people are alike”? It is true that no two people are the same (although twins have the same genes). If there is a form of equality that we share, then it isn't mathematical equality, because humans are not indistinguishable and interchangeable. In fact, a crucial feature of the human condition is diversity.

When the American Declaration of Independence proposed that “All men are created equal”, the concern was with hereditary nobility, not with the idea that our personal genetic heritage causes us to vary in important ways. One of our main challenges in life (especially as an adolescent and young adult) is to figure out what we are good at in comparison to others.

Perhaps it might have been the case that humans were substantially equal in their abilities, interests and motivations. If that were true, then a simple argument could be made for the naturalness of social equality. Our culture is founded on institutionally formalized forms of equality, such as “one person, one vote” and “equality before the law”. Aspiration for greater social equality is also seen as progressive, leading to ideals such as “equality of opportunity.” Yet is naturalness even the strongest argument in favor of social equality? To say that we ought to behave in some way because it is natural has been criticized as the naturalistic fallacy (see Is vs. Ought).

What does it mean to say that any sort of human behavior is natural, given that all human creations (and only human creations) are artificial? The concept of a “state of nature” was developed as a thought experiment to investigate forms of government, but modern thinking on the evolution of human nature is based on the understanding that it is natural for humans to exist in an artificial environment.

That is, humans (as we have come to be) have always existed in an environment that is substantially human created. Although our ability to control the material environment has greatly increased in modern times, our ability to function in the social environment has always crucial in determining our success in life (our ability to raise children similar to ourselves.) The evolution of a human mind capable of culture created a new environment for humans to evolve into: the cognitive_niche. This created a positive feedback where greater mental abilities enabled a more complex social environment, which in turn created pressure for the mental abilities to thrive in that social environment (see Genetic-Cultural Coevolution).

One area of investigation in social sciences such as psychology and anthropology has been identification of universals: what do all people and all cultures have in common? Broad generalizations can be made, but these must be made against a backdrop of diversity. Do we exclude individuals who are mentally ill or disabled? Are we willing to accept that cultural universals must admit some exceptions?

Although innate human behavioral inclinations surely directly underlie many cultural universals, a cultural universal can also arise as a cultural adaptation to some non-cognitive aspect of the human condition. For example, all peoples go through childhood, adolescence, adult independence, and ultimately old age and death.

Cultural diversity is also profound. Our modern way of life emphasizes the importance of particular abilities, and the cultural forms that we use to regulate interaction (market economy, literacy, democracy) represent only a tiny portion of the range of known cultural variation, let alone the presumably infinite space of possible human cultures.

These western cultural forms increasingly dominate the world, displacing other cultures. Why? One answer is that modern cultures have shown an ability to support human productivity, allowing mutually beneficial cooperation to be extended to a far larger scale. Another answer is that our culture has evolved specifically to preserve and propagate itself, in competition with other cultures.

It is incoherent to celebrate cultural diversity without acknowledging that cultures vary in important ways. These differences affect both what it is like to live in a particular culture and also to what degree cultures gain or lose “mind share”. From the perspective of Cultural Evolution we can say that a cultural variant is adaptive in the sense of propagating itself, but there is no straightforward connection between this descriptive statement and any claim that a cultural variant is in some absolute or moral sense superior (see Is vs. Ought). In particular, it is not necessarily the case that a culture which out-competes others will be more pleasant to live in (see the state).