Rock Lee, Guy's student, was taught how to open some of the Eight Gates by Guy. During Part I, he's able to open the first five gates. By Part II, he's able to open the sixth gate. By adulthood, Lee had mastered all eight gates.
Even Mitsuki, a rather mysterious character, was eventually revealed to be the child of Orochimaru through cloning and genetic engineering. The only confirmed parent for Metal Lee is his father, Rock Lee.
In the Third Great Beast Arc, Lee's condition worsens, and Tsunade becomes concerned about him injuring himself again. She removes him from missions, but allows him to keep training after he convinces her to do so. Around this time, Guy arrives with a new student, who easily defeats Lee and injures his ankle.
At a young age, Rock Lee has demonstrated the ability to open the first six gates and an incomplete seventh gate. Lee has also been shown to be able to release the limiters on his eyebrows.