But here’s something you might not know about the third Vice President: Burr had a whole other family of color, having had two children — one of whom is abolitionist John Pierre Burr — with Mary Emmons, a woman from India. The children’s relationship to Aaron Burr was just acknowledged by the Aaron Burr Association in September. On Saturday, that recognition was literally written in stone, engraved onto a new tombstone and placed upon John Pierre’s previously unmarked grave.It’s all thanks to Sherri Burr, a law professor emeritus at the University of New Mexico and author of “Complicated Lives,” which details some of the Burr lineage. Sherri is a descendent of John Pierre. She did extensive research, including DNA tests, on his connection to Aaron Burr in an effort to learn more about her own ancestry. In September, she presented that research at the Aaron Burr Association’s annual meeting.Read MoreAaron Burr had two children with Mary Emmons, a woman from India.The association immediately unanimously voted to officially acknowledge John Pierre and his sister Charlotte Louisa as the children of Aaron Burr — thus legitimizing an entire line of his descendents as his direct descendents.But Sherri said she didn’t do it for herself.”(It was) more important to me to make sure John Pierre got recognized, because he was such an important advocate for eliminating slavery,” she told CNN.John Pierre was well known in Philadelphia at the time. His barber shop was a stop on the Underground Railroad, and both he and his wife, who was likely African American, dedicated themselves to championing the abolitionist cause, said Stuart Johnson, president of the Aaron Burr Association and a descendent of Aaron Burr’s first cousin.”They’ve been overlooked for a long time,” he told CNN. A headstone for John PierreOnce John Pierre and Charlotte Louisa were officially recognized, though, Sherri’s work still wasn’t finished. She found out there was no headstone on his grave in Eden Cemetery and, together with the Aaron Burr Association, she got that changed.The new headstone was made in New Mexico and features a lithograph of John Pierre’s face. It notably includes the text “Son of Vice President Aaron Burr.”Saturday’s ceremony was attended by about 50 descendents of John Pierre, some Johnson said he hadn’t even met before. He said the event was important.”It gives a lot of closure,” he said. But as for Sherri, she’s just glad John Pierre is finally getting the recognition he deserves.”JPB is the person that any Founding Father would have been proud to call a son, and I am humbled to be one of his descendents,” she said.