Assortative mating

The term assortative mating refers to the tendency for people to partner with someone similar. Similar in terms of things like height, ethnicity, religion, language, education, and socioeconomic background.

But how much of this is due to innate preferences, and how much to limited opportunities?

An example of innate preferences would be if women prefer men who are taller than them (which appears to be the case). Then tall women would end up with taller men and short men with shorter women, so couples would (on average) tend to be of similar height.

But consider a scenario where people's main opportunity to socialize is at a local church. Many people would meet their partners there, who would be of the same religion. In this case their similarity would be due to limited opportunities. They might have an innate preference for — or be neutral to — other religions, but have fewer chances to meet those people.

With endless choice, who do we choose?

So, what happens in the world of unlimited choice supposedly offered by online dating?

Do similarities due to innate preferences become more rigidly enforced, because we're better able to find someone who matches those preferences? And do similarities due to opportunity start to fade, as we become less constrained in who we're able to meet?

We actually don't know. Inter-racial, inter-lingual, and inter-religious relationships had all been steadily increasing long before online dating appeared, so it's nearly impossible to disentangle the effect of online dating from that existing trend.

And when it comes to height, education, and income, although there are a few surveys that track those factors in married couples, they don't record whether the couple met online or not. Maybe data from dating apps themselves could be compared with those surveys, but no-one seems to have done that research.

Anyway, it seems plausible that online dating would affect assortative mating, and it would be interesting to test the hypothesis and quantify the effects.