Another week of This Is Us and another bombshell has landed. This time, we might have to consider a seasons-old theory that the Big 3 are not the only Jack Pearson descendants. Once again, Jack (Milo Ventimiglia) takes center stage as Kevin's (Justin Hartley) journey to learn about his father introduces a troubling new piece to the Jack puzzle. After tracking down one of Jack's old war buddies, Kevin is presented with a picture of Jack and a Vietnamese woman wearing the same necklace that Kevin had a meltdown over last season because it was the only thing of his father's he owned.

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The woman will look familiar to eagle-eyed viewers who watched last Tuesday's episode, "Vietnam," which introduced Jack's war storyline. The woman in the photo is the mother of the little boy who offered Jack a fish right after he asked for leave to go find Nicky (Michael Angarano). After this week's reveal, we went back to rewatch Jack and the woman's first meeting, and the heart eyes are pretty obvious.

<em>This Is Us</em>This Is Us

What does this mean, exactly? Well, Hartley told TV Guide before the start of Season 3 that the Vietnam investigation would lead to some revelations about Jack. We can assume that if Jack left Vietnam wearing this woman's necklace that she meant a lot to him, and the picture confirms they shared more than a passing look during his time patrolling her village.

There have been theories about a fourth Pearson child floating around since early Season 1. The leading theory is that if there were another sibling, he or she was the product of an affair, which we'd never believe. However, it's time to consider that Jack started a family when he was in Vietnam with this mystery woman. It might be quite a leap after seeing a picture of her with a necklace, but we have to remember that Kevin is going to find something that makes taking a trip all the to Vietnam worth it. Surely there's someone there worth flying halfway across the world for, right? It could very well be an older half-sibling. This revelation would also make Kate's (Chrissy Metz) comments about being the only one to continue Jack's legacy super ironic.

Of course, there's always the possibility that Jack didn't have a child with this woman, but that she is still significant in some way. The Vietnam storyline could reveal that Jack had a great love before he met Rebecca and something happened to pull them apart. Losing this woman and whatever life they had together could have been the event that shaped Jack's devotion to Rebecca and their later children.

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There's also the question of this mystery woman's son — the one who offered Jack the fish — and how he fits into the story. "Vietnam" gave half a scene's worth of dialogue to one of Jack's cadets who said that kid would eventually grow up to fight for the other side and probably kill the American soldiers there to protect them. This show doesn't shell out throwaway lines, meaning that could be foreshadowing for what's to come for Jack in the upcoming months of the war.

We don't know much at this point, but we do know This Is Us, and that picture isn't just a picture. That look between Jack and this woman isn't just a look. It seems like our perception of the Pearson family and their patriarchal hero is about to shift once more.

his Is Us airs Tuesdays at 9/8c on NBC.

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Mandy Moore and Milo Ventimiglia, <em>This Is Us</em>Mandy Moore and Milo Ventimiglia, This Is Us