There is a religious opinion that the X chromosome is responsible for the formation of evil in a person, and the Y chromosome, on the contrary, is responsible for the formation of good in a person. The combination XY indicates that a struggle is going on inside a person between good and evil. Thus, it turns out that the combination YY is an angel in the afterlife who defeated the evil in himself.
Purely genetically, it is impossible for an individual to exist without an X chromosome, since a person receives one sex chromosome from both parents (always X from the mother, and X or Y from the father). Even if we imagine the creation of such a person in a laboratory, he still will not survive, since about 2000 genes are localized on the X chromosome that encode protein synthesis factors, basic cellular components, enzymes, etc. That is, the X chromosome is vital.