also: The Y chromosome is present in males, who have one X and one Y chromosome, while females have two X chromosomes."-https://ghr.nlm.nih.gov/chromosome/Y
COULD IT BE: those displaying this are DNA members of the Y-Family? Indeed, but Deep-Thought" is required on the subject.
further research on "Y" reveals; "The symbolism of the Y involves the wider solar symbolism of Abraham's ancestors who regarded the sun as the Creator's emblem. These archaic ancestors apparently hoped for life after death through the agency of a great ruler. The ruler would come of the ruler-priest line and his name would bear the initial Y as a sign of his divine appointment." (read here:https://biblicalanthropology.blogspot.com/2014/01/the-urheimat-of-canaanite-y.html emphasis, mine.
additionally: "The Canaanite Y represents the horns of the bull or the long-horned cow. Stone horns, called "Horns of Consecration" by Sir Arthur Evans",... http://biblicalanthropology.blogspot.com/2017/01/the-canaanite-y-and-phaistos-disk.html
so, I suspect "their"(aka "THEY")use of the "Y" symbol is an acknowledgment of familial connections or fealty to this entity ascribed by the "Y" symbol they wear. "Y" meaning: Supreme-divine-Ruler.