by Kevin Currie-Knight
People differ in all sorts of ways. Most of our differences generally go unnoticed when we interact. For example, with regard to a store clerk yesterday, I didn’t notice what her eye color or dominant hand is. But other differences, as the saying goes, make a difference. Historically and into the present, we have put great importance on race, ethnicity, religion, and sexual orientation. What I want to do here is talk a bit about what makes people diverse and why this matters.
The reality of human diversity owes roughly to four factors: biology, environment, culture, and individual choice. Let’s survey each of these.
First and likely the most controversial: Biology. When we are born, we get half of our genes and chromosomes from our mother and half from our father. These combine in a unique way to produce an entirely unique individual. Genes are essentially the construction plan for how our bodies turn out. Of course, this also depends on the environment in which our bodies develop.
It’s not just our bodies that owe something to genetics, but also our behavioral traits. Behavioral Genetics has shown that everything from how optimistic or pessimistic we are to whether we gravitate to religion to how susceptible we are to depression owe at least something to our genetics. If you are skeptical, think of it this way: Our brains help determine our behavior, and our genes play a part in developing our brains.
Of course, a lot of things go into determining our behavioral traits, not just genes, but the rest of the variables we talked about: environment, culture, and individual choice. Therefore, for any particular trait, behavioral geneticists try to determine how much of the trait is genetic and how much is not.
For instance, as of 2021, most scientists put the estimate for the genetic contribution to Attention Deficit Hyperactivity Disorder at 74%, or in scientific terminology, it has a heritability of .74. Journalists might be tempted to write headlines like “74% of your ADHD is in your genes,” but that’s not quite what the figure means.
What scientists do is to test large samples of the population. They figure out how many people – say out of 100 – have ADHD, and then they look to see if the people with ADHD in that sample share certain genetic markers in common. To say that ADHD is 74% heritable means that our of all the people in a population who have ADHD, 74% share certain genetic markers. Or as the psychologist Scott Barry Kaufman says in his book Ungifted: “Heritability estimates are about understanding sources of similarities and differences in traits between members of a particular population. The results apply only to that population. The purpose is not to determine how much any particular individual’s traits are due to his or her genes or his or her environment.”
I mentioned that biology might be the most controversial of the things we talk about, and there is a reason. Until somewhat recently, science has had a fairly bad track record when it comes to using biology to justify racism, sexism, and all sorts of hierarchal categories that rank people by worth. Eugenics used the biology of the time to rank people into genetically fit and unfit, superior and inferior “races,” and was even used to determine who could enter the country or who should be sterilized so that they do not bear “genetically unfit” children. Scientists are a lot more cautious when they talk about biology now, but this is why some are reluctant to talk about the biological roots of diversity.
Let’s move to the environment, by which we mean our physical surroundings. As mentioned, physical and behavioral traits generally have some genetics to them, but they also have environmental aspects. To take an easy one, even identical twins – the only people who share the exact same genetics in common – will often grow to be different heights depending on the nutrition they get and the environment in which they grow up. Or the same identical twins may have the genetic markers that would predict ADHD, but environment – everything from your nutrition to your teachers to your home – plays a significant part.
Next, there is culture, which is our social environment. Anthropologist Clifford Geertz calls culture “webs of significance” spun by networked human beings. What religion people follow, what language you speak, the types of things you and the people around you do for fun, how you collectively understand your lives: these are aspects of culture. And people aren’t just members of one culture at a time, but of various cultures based on the social groups to which we belong. Your fellow church congregants may have one way of acting, while your friends at the skatepark have different ways. You may change the language you use, speaking one way at home, another way with friends, and yet a third way with co-workers. What you are doing is what we all do: learning to behave differently in different cultural settings.
Lastly, there is individual choice. Biology, environment and even culture are things we tend to think of as acting on us. But we also act back on them, at least on environment and culture. Your culture may influence the religion you feel connected to and how you worship, but that’s also a matter of personal choice. Language works the same way: How people around us talk obviously influences the ways in which we talk, but language changes because individuals decide at various points to say things differently, to go against the cultural grain and thereby, individuals shape culture as much as culture shapes individuals. We can choose to change and modify our environments too: I can rearrange the space around me to better suit me, or choose to find or create a new space. Scientists call this “niche construction,” in which we create new spaces in our environment to better suit us.
These four variables – biology, environment, culture, and individual choice – are rarely isolated. They constantly interact with each other, and just about any type of diversity we see around us is influenced by more than one of them. Take a person’s religion. Believe it or not, behavioral geneticists claim that a person’s religiosity has a genetic component; that certain genes predict at least to some degree whether someone will be religious. Even if so, what religion you choose (or don’t) depends on all three other factors too. Where you are born and what religion or religions are dominant is both an environmental and cultural factor that surely influences what religion you will be part of (or whether you will be a part of one). But even with all of that, you are still a unique individual and can decide to turn against all of those factors.
The last thing to note is that there are often heated cultural discussions over what factors are responsible for what kinds of diversity. Are there biological differences between men and women, or are those differences purely because we acculturate girls and boys differently? Is race or gender biological or what we might call a social construction? Are homosexuality or bisexuality genetic, the product of individual choice, or something else? The stories we tell about what produces different types of diversity are important because they can affect how we think about that diversity and possibly how to address inequities it might produce. For instance, cultures have grappled with how to treat gays, lesbians, bisexuals, and trans people, and one piece of this is figuring out whether these things have biological roots or not. Some say that if being gay or trans has a biological origin, we cannot and should not treat them as moral weaknesses or choices people should learn to avoid. Others say that telling biological stories about homosexuality or being trans lays the groundwork for treating them as medical conditions to be cured. Remember what I said about Biology’s unfortunate legacy with issues of diversity.
Another example: Is race biological, or is it a social construct? Our answer to this is important largely because if race is something we’ve socially and culturally constructed – if it has no legitimate biological basis – then we can try to “un-construct” it or construct it in less harmful ways. But, if race does have a biological basis, then we’d have to treat it as more real, and we’d wrestle with the thought that the racial differences that have given rise to racism are here to stay.
Of course, there is a difference between the sources of diversity and what we make diversity mean. For instance, it can be true that skin color or other physical features we use to construct racial boxes are genetic without the racial boxes – let alone whatever significance we think they have – being genetic too. And it doesn’t seem clear that we need to decide whether being gay is genetic or a choice to determine whether we should treat gay people with respect and acceptance. We’ll talk about all of that, though, in another essay. Suffice it to say that all the diversity we see between humans has a source – really, multiple sources – and while we don’t always handle diversity well, it can be important to identify where it comes from.