Irish twins 

Children, born in succession within one year

They were like rabbits. Now their Irish twins are six and seven.

Irish twins by cornholio October 16, 2003

Irish twins 

Siblings born within 12 months of each other.

My sister and I were born 11 months apart. We were known in our family as Irish twins.

Irish twins by Al Pearson June 6, 2004

Irish Twins 

The roots of the idea behind the term are actually quite old, although no one knows when, exactly, people first began to talk about Irish twins. In both England and the United States, a massive influx of Irish immigration in the 1800s led to a negative connotation with Irish people and society. This often happens when a large immigrant group begins to settle in mass numbers in a new country. The Irish were accused of being backwards and uncultured, and it was assumed that they were uneducated, dirty, and a general pox on society. As a result, the use of the word “Irish” began to be pejorative.

A number of derogatory terms incorporating stereotypes about the Irish began to emerge, including “Irish confetti” for thrown bricks and “Irish kiss” for a slap. Irish twins fits into this vernacular, and is actually insulting on multiple levels.

Firstly, the term pokes fun at the stereotypical fertility of Irish Catholic families, which traditionally do not use birth control. In addition, it implies that the Irish lack the ability to plan ahead or control themselves, having children in quick succession rather than responsibly spacing them. Finally, it suggests that the Irish do not understand the medical definition of twins, which involves two children conceived and born together.

guy#1dudearetheytwins?

guy#2yea"Irish Twins"...

guy#1 huh?

guy#2 theywereborninthesameyear..thereirish

Irish Twins by luckyLETTE May 12, 2010

Irish twins 

two people born less than 12 months apart (from the stereotype that Irish Catholics have many children)

They ended up with Irish twins and shortly after, decided they would be better off with a larger house.

Irish twins by The Return of Light joker January 1, 2009

Irish Twins 

siblings who are born less than twelve months apart

i swear their parents rut like bunnies. debbie and jim are irish twins: ten months apart!

Irish Twins by RobThrobs October 21, 2010

Irish twins 

Two siblings who are not twins but born in the same year, usually nine months apart.

Are Andie and Jack McPhee Irish twins?

Irish twins by not a caker yo April 17, 2004

Black Irish Twins 

Siblings born in the same year to different mothers.

A pun on Irish twins, Black Irish, and the multigenerational deterioration of African-American families.

NB: You don't have to be Black to have a Black Irish Twin.

The other eighth graders thought Dion and Errol were kidding about being "brothers from another mother," but they mean it literally since they were Black Irish Twins.

Black Irish Twins by PBMax February 23, 2008