Given news of the recent relationship between Rob Kardashian and (possibly pregnant?) Blac Chyna, if Rob's half-sister Kylie Jenner and her longer-term partner Tyga—who is father to ex-fiancée Chyna's kid—get married, it may open a vortex into an incredibly complex family tree. The intrigue of celebrity life is highest when high drama ensues in the spotlight as well as at home. Because fame presents the problem of how to separate one's public and private lives, part of the celebrity struggle is balance.
The family lives of celebrities have long captivated public interest, and that truth is obvious with the Kardashians. Dubbed "America's First Family" on the cover of Cosmopolitan magazine in late 2015, the Kardashian clan is famous in part for their success at courting controversy throughout their extensive, complicated family.
David Allen Lambert is the chief genealogist for the New England Historic Genealogical Society. "Obviously, Kris Houghton Kardashian Jenner is the mom of Rob and Kylie," he tells Broadly. Though people in their situation often refer to each other as simply sister and brother, Lambert says that, from a legal perspective, Rob and Kylie are just half-siblings. According to him, if Kylie marries Tyga she will become the stepmother of his and Chyna's son, King Cairo Stevenson. "However, if they just remain boyfriend and girlfriend, she's nothing."
If the new relationship between Rob and Blac Chyna endures and they one day wed, that will further complexify their genealogical map. Kylie would then become step-aunt to King Cairo as well as his stepmom. "[Rob] would also be the step-uncle of any children Kylie Jenner has, regardless if he marries Blac Chyna. He would also become the step-uncle of King Cairo if his step-sister Kylie marries Tyga."
Lambert says that the Kardashian-Tyga-Chyna family tree would have an "interesting mix" of autosomal DNA. Autosomal DNA looks at the 23 chromosomes that people inherit from their parents and grandparents, Lambert explains. "It's good for back to about 5 or 7 generations. A lot of people have a narrow focus on their ethnic diversity in their family. When you have more different countries that show where your ancestors come from, it's kind of cool."
If, as recent speculation suggests, Blac Chyna has a child with Rob, then that kid would be to King Cairo as Kylie is to Rob. "King Cairo and [the baby of Rob and Blac Chyna] would be half-siblings, echoing Kris Houghton marrying Robert Kardashian, then Bruce, [who became] Caitlyn Jenner." The Kardashian-Jenner family is well fleshed out in the media, so unless there's some unknown family cousinship between Blac Chyna or Tyga's families, Lambert says this is just about as complex as this family tree would become. "There's no royal lines that I know of. But obviously, they're looked at as American royalty by the media," he says.