My best guess is that this myth about the virgin birth derives from The Gospel of the Buddha by Paul Carus, published in 1894.
His wife Maya-devi was beautiful as the water-lily and pure in mind as the lotus.
As the Queen of Heaven, she lived on earth, untainted by desire, and immaculate. [2]
The king, her husband, honoured her in her holiness,
and the spirit of truth, glorious and strong in his wisdom
like unto a white elephant, descended upon her. [3]