Answer by taking a quote from the following article:

John Anthony Gillis was born in Detroit, Michigan, the youngest of ten children--and the seventh son--of Teresa (nee Bandyk) and Gorman M. Gillis. His mother's family was Polish, while his father was Scottish-Canadian. He was raised a Catholic, and his father and mother both worked for the Archdiocese of Detroit as the Building Maintenance Superintendent and secretary in the Cardinal's office, respectively. Gillis became an altar boy, which landed him an uncredited role in the 1987 movie The Rosary Murders, filmed mainly at Holy Redeemer parish in southwest Detroit.

White has been called "eccentric." He is known for creating mythology around his endeavors; examples include his claim that the Stripes began on Bastille Day, that he and Meg are the two youngest of ten siblings, and that Third Man Records used to be a candy factory. These assertions came into question or were disproven, such as when, in 2002, the Detroit Free Press produced copies of both a marriage license and divorce certificate for him and Meg, confirming their history as a married couple. Neither addresses the truth officially, and Jack continues to refer to Meg as his sister in interviews, including in the documentary Under Great White Northern Lights, filmed in 2007. In a 2005 interview with Rolling Stone magazine, Jack alluded to this open secret, implying that it was intended to keep the focus on the music rather than the couple's relationship:  "When you see a band that is two pieces, husband and wife, boyfriend and girlfriend, you think, 'Oh, I see...' When they're brother and sister, you go, 'Oh, that's interesting.' You care more about the music, not the relationship--whether they're trying to save their relationship by being in a band."  He has an attachment to the number three, stemming from seeing three staples in the back of a Vladimir Kagan couch he helped to upholster as an apprentice. His business ventures frequently feature "three" in the title and he typically appends "III" to the end of his name. During the White Stripes 2005 tour in the UK, White began referring to himself as "Three Quid"--"quid" being British slang for pound sterling.  He maintains an aesthetic that he says challenges whether people will believe he is "real." He frequently color-codes his endeavors, such as the aforementioned Third Man Upholstery and The White Stripes, as well as Third Man Records, which is completely outfitted in yellow, black, red, and blue (including staff uniforms). As a taxidermy enthusiast--that correlates to his work as an upholsterer--he decorates his studio in preserved animals, including a peacock, giraffe, and Himalayan goat.

what was mythological about it?
examples include his claim that the Stripes began on Bastille Day, that he and Meg are the two youngest of ten siblings,