Assortative Mating

Assortative mating (also referred to as positive assortative mating or homogamy) is a mating pattern and a form of sexual selection. It means that individuals with similar phenotypes mate with one another more frequently than would be expected under a random mating pattern. Some examples of similar phenotypes are body size, skin coloration or pigmentation, and age. Assortative mating can increase genetic relatedness within the family and is the inverse of disassortative mating.

In addition to genetic assortative mating, humans also demonstrate patterns of assortative mating based on sociological factors as well. Sociological assortative mating is typically broken down into three categories, mate choice based on socio-economic status, mate choice based on racial or ethnic background, and mate choice based on religious beliefs.[15] Assortative mating based on socio-economic status is the most broad of these general categories. It includes the tendency of humans to mate within their socio-economic peers, that is, those with similar social standing, job prestige, educational attainment, or economic background as themselves. This type of assortative mating includes the growing tendency in recent years for humans to marry people more like themselves in educational attainment or earned income. This applies across all socio-economic statuses, both rich and poor, in that the rich and well educated tend to marry among themselves, as do the poor and under educated. This is best observed in the fact that, in the United States, matches among those with similar educational attainment were more common than they would have been if couples had matched randomly. https://en.wikipedia.org/wiki/Assortative_mating (source of lowering Income Mobility?)