Irish Twins Are Siblings Born Less Than a Year Apart

Irish twins

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"Irish twins" is an outdated term used to describe two children born to the same mother in the same calendar year or within 12 months of each other. Irish triplets are when three children are born to the same mother within three years.

For example, a mother gives birth to one baby in January of 2017 and another child in December of the same year. Or, alternatively, a mother births a child in August of 2017, becomes pregnant again in October and gives birth to another child in July of 2018.

A more updated term would be closely spaced siblings or close-in-age siblings. Those terms have the advantage of not bringing up the question as to whether the siblings are really twins.

Are Irish Twins Technically Twins?

Irish twins are not technically twins, meaning two people born from the same gestational period. It's a colloquial way to classify siblings that are born close together. Sometimes the use of the term Irish twins is expanded to describe any siblings that are close in age. Some even stretch the definition to include siblings less than two years apart. Some would call that "almost Irish twins" or "practically Irish twins."

If you're referring to twins born in Ireland at the same time to the same mother, they a true Irish twins. But if they are born months apart, they don't meet the dictionary definition of twins. The first is quite literal: “either of two children brought forth at a birth” ( or “either one of two babies that are born at the same time to the same mother” (Merriam-Webster). By that definition, Irish twins are not twins. Twins are two children born from the same conception, carried during the same pregnancy, and born together.

Twins Aren't Necessarily Born on the Same Day

Because of reproductive and medical technology, one can put forth examples of all kinds of exceptions that violate the dictionary definition but produce individuals that would still be considered twins. For example, in-vitro twins, or in the case of frozen embryos. There can also be delayed-interval birth where twins have different birthdays, days or even weeks apart. The Guinness world record is for twin sisters born 87 days apart—and who happen to have been born in Waterford, Ireland.

Origin of the Phrase 

The phrase originated as a derogatory term associated with Irish immigration to the United States and England in the 1800s. The implication was that groups of close-in-age siblings were a characteristic of large Irish Catholic families.

In modern use, the term is not intended as an insult, but rather as classifying siblings born close together. A family might proudly claim the term to describe the short time span between the births of their children. You and your close-in-age brother or sister might tell others that you are Irish twins. However, use caution when using this term about other families. There may be reasons a family has children close together in age that they would prefer not to discuss.

Are Closely-Spaced Children as Challenging as True Twins?

Both parents of twins and parents of closely-spaced children have much to add to the debate over which circumstances are more challenging. But most will agree that having twins is not the same as having Irish twins. One or the other may be easier or more difficult, but they’re not the same thing.

Some of the issues of raising closely-spaced children may be similar to what parents of twins face. You may have two in diapers at the same time, two cribs, two high chairs, and the need for a double stroller. Sometimes, Irish twins 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. A newborn and a 10-month-old baby have vastly divergent developmental capacities. A 9-year-old and a soon-to-be 10-year-old may not appear quite so distinct. 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 for families for many different reasons. Be sensitive as discussing it may bring up personal issues that a family would prefer to keep private.

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