Do you know all 16 of your great-great grandparents and are they all from Wales? If so, have you tested with AncestryDNA, Family Tree DNA, MyHeritageDNA, or 23andMe (before Aug 2017)? Then please share your GEDmatch ID. https://www.wikitree.com/wiki/Space:Autosomal_DNA_Ethnic_Admixture_and_Ancestry
Thanks and sincerely,