Confirmation bias, also called confirmatory bias or myside bias, is the tendency to search for, interpret, favor, and recall information in a way that confirms one's preexisting beliefs or hypotheses. ... The effect is stronger for emotionally charged issues and for deeply entrenched beliefs.
Confirmation bias - Wikipedia
https://en.wikipedia.org/wiki/Confirmation_bias
There's no evidence of an indigenous pygmy presence in Ireland (let alone one which was driven out of existence by the Irish).
There are a bunch of facebook / pinterest / etc posts by people passing along stories of black leprechauns as some kind of fact, but a bunch of people sharing facebook nonsense doesn't make it become true.
"1 per cent of all Scotsmen are direct descendants of the Berber and Tuareg tribesmen of north Africa, a lineage 5,600 years old...Geneticists at Trinity have already shown that the Irish hold one of the purest remnants of the pre-Neolithic hunters and gatherers of southern Europe. Men with Gaelic surnames, and almost all the men of Connacht, carry the oldest genes of all...the flow of life to Ireland was undoubtedly enriched originally by the tribes from the mountains and sands of Africa...The Berber and Tuareg heritage now showing up in Scottish genes is just another support for the abundant “Celtic” associations found in north Africa, in song and singers, archaeological monuments, manuscript decoration and jewellery design. Such treasures as the Ardagh Chalice and Book of Durrow show intricate affinity with Islamic decorative motifs and crafts, and Coptic Christianity from Egypt left material traces well ahead of St Patrick."
https://www.irishtimes.com/news/env...-why-celtic-dna-leads-back-to-africa-1.522345