Having watched the Madness in the Fast Lane videos,  I also believe it’s possible for these twins to be hybrids.  Their manic behavior could be explained by various

mental or physical anomalies,  but the explanations are really narrowed down when it comes to their bizarre ability to bounce back after being hit by trucks,  jumping

off a bridge,  etc.  That is supernatural,  possibly demonic possession but I think hybrid is just as likely.

 

an article on the subject of hybrids:     http://www.khouse.org/articles/1997/22