Roger is not Geillis's son in Outlander
There was no way for Roger to ever be born there. Roger is not directly related to Geillis, but she is his great-great-however-many-times-grandmother. Likewise, Dougal is Roger's grandfather many times removed. Geillis and Dougal's son is William Buccleigh MacKenzie.
William Buccleigh MacKenzie is the illegitimate son of Dougal MacKenzie and Geillis Duncan, and was raised by William John and Sarah MacKenzie.
In Scotland in 1968, Claire tells Roger Wakefield that Geillis Duncan was his ancestor and that she was burned as a witch in 1743.
She is Dougal's grand niece through Jamie, and Roger is a distant descendant.
Murtagh is often mistaken for Jamie's father, but he is actually his kindly godfather. He is not married and hasn't fathered any children.
“He's about 25,” Gabaldon said. It's an interesting response. If you're up to date on the series, then you know that Jamie is not dead at the age of 25.
It's possible that Amelie's sister is the one who gives birth to the line that leads to Claire. Fergus will still be an ancestor but not a direct ancestor and that would mean Laoghaire isn't one of Claire's ancestor.
Geillis and Dougal's son was adopted by a family in Cranesmuir, and he grow up to be William Buccleigh MacKenzie, also known as Buck.
Brianna and Roger are distantly related, as they are both direct descendants of Jacob and Anne MacKenzie. Brianna is their great-granddaughter through their daughter, Ellen, who was Jamie Frazer's mother. Roger's ancestry goes back directly to Jamie's uncle, Dougal Mackenzie, who was Jacob and Anne's son.
Finally we discover how she survived: Because she was pregnant, they didn't burn her straight away. Dougal, bless his foolish soul, came to get the baby and helped her escape.
William loses both his mother Geneva, who dies during childbirth, and his supposed father the Earl (killed by Jamie), shortly after his birth, from there he ends up in the care of Jamie's friend and close confidant Lord John Gray - who had married Geneva's sister Isobel.
“I curse you. I curse you with knowledge, Jack Randall. I give you the hour of your death. Jonathan Wolverton Randall, Born Sept 3rd, 1705, dies…” she whispers in his ear, and suddenly he knows that she's telling him the truth.
Claire asks Lord John if he believes she (and Brianna and Roger) are from the future, to which he says that he doesn't, but that he will behave for all appearances as though he does.
Geillis Duncan (Buck's mother and Roger's many times-great-grandmother) comes back into play and performs some kind of sex act with Buck (the time-traveling version of her as-yet-unconceived son).
Following Aaron Beardsley's death, her mother Fanny gave birth to her while traveling to Brownsville. Knowing the child was half-black, Fanny abandoned her newborn daughter, fearing the repercussions of her adultery.
In Outlander Season 3, Episode 13, Geillis gives Claire a quick rundown of the events that happened. Geillis gave birth to the baby, who was given to William John and Sarah MacKenzie, the couple whose baby had been “taken by the faeries.” After that Dougal was able to smuggle her out.
Margaret's vision produces the following information: "When twice 1,200 moons have coursed, 'tween man's attack and woman's curse, and when the issue is cut down, then will a Scotsman wear a crown.” To put it simply, it's Brianna, the baby who was born 200 years after she was conceived.
He may never have called Jamie “Dad,” but Jamie has been the only father figure he's ever known. He's always looked up to Jamie, and this moment shows that Jamie continues to respect Fergus and call him family. There are sadly some who wouldn't view adopted sons and daughters in the same way as biological ones.
Who is Fergus Fraser's real dad in Outlander? French businessman and merchant The Comte St. Germain (Stanley Weber) is revealed to be Fergus' father.
But then — BUT THEN! — Claire's necklace turns black, signaling that Master Raymond slipped real poison into the cup.
Over the course of the first season, Claire and Jamie fell in love and married while Frank was back in the 20th Century. It quickly became clear Jamie's ghost was trying to find his beloved which is probably why he was watching Claire.
Because yes, Claire and Lord John end up married in book seven, and yes, they drunkenly (and full of grief for the loss of Jamie, whom they both love with all of their heart) consummate that marriage. And then Jamie shows up alive and well!
Jeremiah Alexander Ian Fraser MacKenzie, commonly called Jem or Jemmy, is the son of Brianna and Roger MacKenzie, and grandson of Claire and Jamie Fraser.