Demographic trends tend to play out on the timelines of multiple generations. Declining birth rates, increased life spans and widespread lifestyle changes can all have a dramatic impact on not only what our families look like, but also how we connect with them. And because families are the nucleus of our world, changes in families mean fundamental changes in us: who we are, what we believe and how we connect with our world.

I have previously written about one such trend – a surplus of grandparents. The ratio of grandparents to grandchildren has never been higher than it is right now, thanks to increased life expectancy and a declining birth rate. It’s closing in on 1:1, meaning for every child, there is one unique grandparent. As a grandparent, I have to believe this is a good thing.

But another demographic trend is playing out and this may not be as positive for our family structure. While the grandparent market is booming, our supply of cousins is dwindling. And – as I’ll explain shortly – cousins are a good thing for us to have.

But first, a little demographic math. In the U.S. in 1960, the average number of children per household was 3.62. This was a spike thanks to the post WWII Baby Boom, but it’s relevant because this generation and the one before were the ones that determined the current crop of cousins for people of my age.

My parents were born in the 1930s. If both of them had 3 siblings, as was the norm, that would give me 6 aunts or uncles, all having children during the Baby Boom. And each of them would have 3 to 4 kids. So that would potentially supply 24 first cousins for me.

Now, let’s skip ahead a generation. Since 1970, the average number of children per household in the U.S. has hovered between 1.5 and 2. If I had been born in 1995, that would mean I only had 2 aunts or uncles, one from my mother’s side and one from my father’s. And if they each had 2 children, that would drop my first cousin quota down to 4. That’s 20 less first cousins in just one generation!

But what does this lack of first cousins mean in real terms? Cousins play an interesting sociological and psychological role in our development. Thanks to evolution, we all have something called “kinship altruism.”  In the simplest of terms, we are hardwired to help those with which we share some DNA. Those evolved bonds are strongest with those with whom we share the most DNA. There is a hierarchy of kinship – topped by our parents and siblings.

But just one rung down the ladder are our first cousins. And those first cousins can play a critical role in how we get along with the world as we grow up. As journalist Faith Hill said, writing about this in The Atlantic, “Cousin connections can be lovely because they exist in that strange gray area between closeness and distance—because they don’t follow a strict playbook.”

As Hill said, cousins represent a unique middle ground. We have a lot in common with our cousins, but not too much. Our cousins can come from different upbringings, can span a wider range of ages than our siblings, can come from different socio-economic circumstances, can even live in different places. We may see them every day, or once every year or two. Yet, we are connected in an important way. Cousins play a critical role in helping us navigate relationships and learn to understand different perspectives. Having a lot of cousins is like having a big sandbox for our societal development.

If you overlay societal trends on this demographic trend towards fewer first cousins, the shift is even more noticeable. We are a lot more mobile now then our parents and grandparents were. Families used to generally live close to each other. Now they spread across the country. My wife, who is Italian, has almost 50 first cousins and almost all of them live in the same town. But that is rare. Most of us have a handful of cousins who we rarely see. We don’t have the advantage of growing up together. At a time when societal connection is more important than ever, I worry that this is one more instance of us losing the skills we need to get along with each other.

From my own experience, I have found that the relationship between my cousins is vital in negotiating the stewardship of our families as it’s handed off from our parent’s generation to our own. I personally have become closer to many cousins as – one by one – our parents are taken from us.  Through our cousins – we relive cherished memories and regain that common ground of shared experience and ancestry.