Waluigi is a product of incest. In the Mario universe, it is never clear who Waluigi’s parents are or were. One could assume that the identies of his parents are up to interpretation, but when you look further into Waluigi’s life, it is clear that he is, in fact, a product of incest.
Why, you may ask? The answer is simple. Waluigi has a defining characteristic that ties back to royal inbreeding in Europe. Waluigi has an abnormally large mandible, also known as the jawbone, that protrudes forward far past the upper jaw. The history of this facial deformity draws directly back to the House of Habsburg, a royal family that held the throne of the Roman Empire from 1438 to 1740. The Habsburg family had so much incest that their family was riddled with physical (and probably mental) deformities. The most well-known deformity stemming from this family’s incestual relations is the Habsburg Jaw.
The Habsburg Jaw is defined as ‘a physical condition known by the modern term mandibular prognathism. It is characterized by a jutting lower jaw that is often accompanied by an abnormally thick lower lip and sometimes a tongue that is abnormally large’. This description matches Waluigi’s jaw shape exactly. Coincidence? I think not.