https://www.gamespot.com/articles/red-dead-redemption-2-marks-the-return-of-an-unexp/1100-6461056/

We've finally learned a lot more about Red Dead Redemption 2 now that we've gotten to go hands-on with it. That includes discovering a ton of new mechanics, from the big (like weapon degradation) to the small but delightful (you can lose your hat and then pick up someone else's). Before this huge information drop, we only knew what we could glean from trailers. One of the notable tidbits we had learned concerned its story. We know that, as a prequel, this tells the story of Dutch's gang, where the first game's protagonist, John Marston, made his outlaw name. However, the new trailer reveals that his family is along for the ride too.

In a pair of blink-and-you'll-miss-it cameos, we see both Abigail Marston and her son, Jack. Both of them are sitting at a campfire as the gang gathers around. In a separate scene, Abigail talks to Morgan one-on-one, and the mini-map at one point shows an "A" icon--possibly for Abigail. It seems the whole Marston family will factor into this story.