He left when he was six, the age he was in the flashback from last week. Spencer never said he was only gone a few years. He said in the pilot that he doesn’t have a father cause he’s been gone that long. Spencer is just in high school 16-17 so that time lines up. Dylan would have been a baby or she was pregnant with him as I mentioned in the prior ask message edit. Billy is from the neighborhood and knew Grace prior to him coming to see Spenser play and as we found out last night they (he and Grace) were an item in high school. That’s pre- Spencer, which no one but he and Grace knew we can assume for now.

In some stuff I’ve read, April, who was the previous showrunner and still show creator said it’s not meant to drag out the entire season and Jordan is gonna start looking into things- which got set off by his find last night it seems

I posted this article over here but here’s the quote from her in tvguide about that. This was after the pilot

. When are we going to find out what “the truth” is Coach Baker is referring to at the end of the episode?
April Blair: It will come. We’re not gonna draw it out too much. I mean, there are layers of secrets that Billy and Grace are keeping, but the kind of big one, [the] answer about his father, will come within the first few episodes. Because I hate that, when someone just draws out a thing forever… In Episode 3, Jordan starts to find clues into that. Jordan becomes the audience. He’s really gonna tell the story of getting under the hood of, “Why does my dad seem so invested in this guy?” and starts to piece together clues that leads him on the path to helping us discover Spencer’s parents question. It won’t go on. It won’t drag on. It’s not like an episode-y kind of situation. (x)

Well first let me say I never thought Jordan and Olivia were twins or not theirs nor do I think Spencer is Billy’s son still- no matter how hard they troll us with Billy and Grace’s backstory  I just find it really hard to believe that to be the route this all goes to because they’ve been too obvious with it to make folks jump to that conclusion and two, I can’t see the Spencer we’ve met continue to just be cool to stay with them and continue to play for him if it came out as such. The show, I know is loosely based off true events as well but even that as the not true twist seems like a bit of a stretch to me.

And also there’s Dylan. I think it’s hasty and side-eye worthy to assume he and Spencer have different fathers just cause we know now Billy and Gracie dated back in high school. It’s been stated that Spencer’s dad, Corey, left to take a job and never came back so that would be the reasoning if that holds up as true. Edit to add: It’s been said he left when Spencer was 6 and Dylan looks about 10 or 11 so him leaving with her pregnant with him or a infant can hold up

Maybe Spencer and Dylan’s dad is why they (Billy and Grace) split back in the day. It took something along with NFL recruiting to get Billy out of Crenshaw himself and to his current wife, kids, and Beverly to stay cause clearly we saw last night he has somewhat forgot where he came from.