This increase in physical strength and prowess is due to "hybrid vigor", a common occurrence between two closely-related species, where the offspring gains the best aspects of his parents. While most ivory elves are the result of crossbreeding, some are simply the offspring of two ivory elven parents. A tale of an ivory-drow that was without weakness to light or dark, had gray skin and white hair who fought with determined malice has long been a favorite of bardic tales, but the accuracy surrounding it has never been substantiated.