i have thought about who Trubel's real parents could be, and after been reading a lot on this Wikia and see a lot of episodes, could it be possible that Trubel was either the kid of Nick's Aunt Marie or Uncle George (i know that Marie possible was with Farley Kolt and George was'nt a Grimm like his sisters, but Marie could have gotten a child without Kolt, and George could have married a Grimm)