Years ago, when two children were born within 12 months of each other, people often referred to them as "Irish twins." And when three children were born to the same mother within three years, they were called "Irish triplets." But today these phrases are outdated and rarely used.

The Origin of "Irish Twins"

The phrase "Irish twins" originated in the late nineteenth century as a derogatory term associated with Irish immigration to the United States. The implication was that groups of close-in-age siblings were a characteristic of large, mostly poor, Irish Catholic families.

In fact, it was common for Irish immigrants to have children close in age because they followed the Church's strict guidelines regarding contraception. Back then, when the phrase was used, the person was stereotyping the Irish and implying that they were uneducated, poor, and lacked self-control.

Today, the term is not intended as an insult, but rather as a way of classifying siblings born close together. For instance, some families might proudly use the term to describe the short timespan between the births of their children. However, you need to be cautious when using this term when talking to families other than your own.

Using the phrase "Irish twins" is not only slang but it also disparages the Irish culture and can be offensive —even if you are using it affectionately.

It's more appropriate to simply recognize that the children are closely spaced siblings or close-in-age siblings or to say nothing at all about their ages.

Are Irish Twins Technically Twins?

When people refer to Irish twins, it's important to recognize that although the siblings are close in age, they are not technically twins. In other words, they were not born during the same gestational period. Calling them Irish twins is an informal way of classifying siblings that are born close together.

On the other hand, if you're referring to twins born in Ireland at the same time to the same mother, they are true Irish twins. But if the children are born months apart, they don't meet the true definition of twins. Twins are two children born from the same conception, carried during the same pregnancy, and born together.

Of course, because of reproductive and medical technology, there are all kinds of exceptions that produce children that would still be considered truly twins. For example, there are in vitro twins. There also can be a delayed-interval birth where the twins have different birthdays—one is born on one day and one is born the next. It's even possible for twins to be born days or even weeks apart.

According to the Guinness World Record, the longest interval between the birth of twins is 87 days apart for two sisters born in 2012—who ironically were born in Waterford, Ireland.﻿﻿

Parenting Challenges

Even though there are challenges with having twins and challenges with having closely-spaced children, most people agree that having twins is not the same as having Irish twins.

Some of the issues of raising closely-spaced children may be similar to what parents of twins face. You may have two children in diapers at the same time, two cribs, two high chairs, and the need for a double stroller.

Sometimes, closely-spaced children can even end up in the same grade at school. They may have the same friends, enjoy the same activities, and generally live a similar lifestyle as they grow older, much in the way that twins would. If they are born 12 months apart, they may even have the same birthday, or be close enough that your family celebrates them together.

Arguably, the experience is more diverse with younger children. For instance, a newborn and a 10-month-old baby have vastly different developmental capabilities. Meanwhile, a 9-year-old and a soon-to-be 10-year-old may not appear quite so distinct. Then, as puberty approaches, the differences may become more pronounced, then less distinguishable as the children grow up.

A Word From Verywell

Having children close together can be a choice that some families make. Or, it may be that the pregnancy was unexpected. Either way, you may want to refrain from discussing the situation or pointing it out. There may be some personal issues regarding the spacing of the children that a family would prefer to keep private.