Id like to know where this term originated, and its meaning.

Black Irish
From Wikipedia, the free encyclopedia

For people of African descent in Ireland, see Afro-Irish people.
For the cocktail sometimes called a "Frozen Black Irish", see White Russian (cocktail)#Fresh cream substitutions.
For the film by this name, see Black Irish (film).

Black Irish is a traditional term believed to have originated in the United States that commonly ascribes to a dark brown or black hair phenotype appearing in Caucasian persons of Irish descent. This can be distinguished in contrast to the (lighter) brown, blond or red hair color variant, the latter stereotypically perceived to personify the look of typical Irish folk.[1] The term itself is rather ambiguous and not frequently used in everyday conversation. As such, the description of those it depicts has been known to vary to a degree in that some have differing views on which physical characteristics (e.g. dark hair, brown eyes, medium skin tone or dark hair, blue eyes, pale skin tone) best define the appearance of the so-called Black Irish.

Inspired by tales which claim the darker features to be of Iberian derivation,[3] knowledge seekers have looked to science for answers, often citing genetic studies pertaining to those with Irish (and/or British) ancestry. This is seen as a means of determining what genotypic and environmental factors have contributed to the divergence between the more or less prevalent types found among Irish people.