Masters of Sex made a bold return Sunday. The Showtime drama’s season three opener was less about sex and more about the consequences that accompany it — kids, that is.

It’s now 1966, four years from when we last saw Bill Masters (Michael Sheen) and Virginia Johnson (Lizzy Caplan) at the conclusion of season two, and they’re getting ready to publish their groundbreaking book, Human Sexual Response. Both are still struggling to meet the demands at home, however — a part of their lives the premiere chose to focus heavily on.

For starters, Virginia’s children have grown up considerably: she accidentally walks in on her son having sex, and later her daughter tries to seduce Masters. This all happens on a casual group vacation between their two families, which seems to suggest that Libby is now A-OK with the three-way marriage.

But for a show that normally revolves around very adult material, it was a startling shift in subject matter to suddenly delve into rebellious teens, parental disciplining and, as revealed in the last minutes of the episode, another pregnancy. The show, which has been a critical darling since it debuted in 2013, has drawn some critical backlash with its return.

"[The kids] have been around previously, but never intrusive or — more importantly — essential," wrote The Hollywood Reporter's television critic Tim Goodman in his review. "[It's] problematic in that people are tuning in for Masters and Johnson and not really for their kids ... Children are often boring."

Showrunner Michelle Ashford is aware of the criticism and insists that the show is not reinventing itself as an ABC Family drama. "I do sense that people are a little worried that somehow we’ve turned into some kind of weird family show," she tells THR, insisting that the children will not remain the focus as the season moves along. "It’s still very much grown-up subject matter."

Ashford acknowledges that the new season brought a lot of changes at once. “I know we threw a lot of people in the first episode, and it’s taking them a moment to get used to it. We’re really sensitive to the fact that we’re asking a lot of people, and we don’t want to whiplash them too much. We’re aware that viewers want continuity, so next year is not going to be 10 years down the road. We want to keep it together here for a bit.”

In a candid conversation with THR, Ashford also explains the reason for the time jump, why Masters still isn’t exactly a likeable character and the "astronomical legal hurdle" that went on behind the scenes.

Why did you decide to fast-forward four years?

It was really a rather placid time. Essentially what [Bill and Virginia] did for ten years was accumulate research. Everything was on track: they were working, collecting, writing, etc. Then they presented their book. When you’re telling a story that spans 30-plus years, you want to get to the part where things change for them significantly, so we felt like we needed to make a fairly big leap. Of course, there is a lot that comes with a change like that. I know these jumps can be a little disconcerting, but once we settle in we’ll just be going straight ahead for the rest of the season — no more time jumping. ... You have to re-ground yourself. It was tough to figure out how to keep the characters themselves and yet move them through time like this.

What did we miss in that period of time?

Bill and Virginia became more comfortable with being a couple, and Libby became more comfortable with realizing that this was going to be a permanent part of her life and that she needed to make peace with it. One of the other things I miss is that we didn’t get to see the end of Libby’s relationship with Robert. It would have been nice to see how that one played out. We’re going to have to piecemeal reveal to the audience what happened there over this season since his character will not be back.

One of the biggest surprises in the season opener is just how much Virginia and Bill’s kids have grown up.

If you’re moving through time, it’s kids that always change the most. Virginia’s daughter, Tess, was 12 years old when we last saw her and if you age her up with the four-year time jump we’ve made, you end up with a 16-year-old — a radically different creature than a 12-year-old.

They had a considerable amount of screen time in the season premiere. Will the kids continue to be a central part of the season?

No, I do sense that people are a little worried that somehow we’ve turned into some kind of weird family show. That was all intended to show more how these characters interact now, and they are this bizarre, blended family. And it’s true — the Masters and the Johnsons would go on these family vacations together. But no, we’re still going to be concentrating on Bill, Virginia, Libby and what’s happening with them and their work.

If you look at Tom Maier’s book [on which the show is based], there is no question that their parents’ work and lives still affected them. We don’t know a ton of information, but it seemed negligent to not mention this at all. And the children are even used as mirrors for what has happened with the grown-ups and how their behavior ripples down through their progeny. But as you’ll see, it rights itself back to very adult storytelling.

What’s the story behind the disclaimer at the end of the episode that notes that Tessa, Henry, Johnny and Jenny are “entirely fictitious?”

We were presented with an astronomical legal hurdle this year that I can’t really speak to, except to say that there were certain things that had to be done in our storytelling that had to do with legal issues. So, we made lemonade out of lemons. The fact is that some of those events were not necessarily the story we were going to tell. But we’ve told them at the very beginning of the season, and then we move on and we pick up back where we had intended this season to start. In an odd way, those first two episodes are to explain a lot of stuff that ends up not actually being so instrumental to the storytelling, but once we were in that area, we decided to make the most of it.

When did the legal concerns arise?

We live in a world where we’re dealing with corporations and they have legal teams. It became apparent when the kids became teenagers. There was just a lot of stuff that happened that we needed to deal with, and we feel like we’ve dealt with it at the very beginning of the season and now we’re moving on and getting back to our story. As you see in the beginning of this season, they each have three kids. In reality, they each had two kids. That’s just about the most I can say about that. At some point, it is a really fascinating story about how this stuff goes down with this clash between fiction and nonfiction and how that affects how we tell stories and our lawyers who are looking at it very differently than us.

Kids and legal issues aside, the series has had a stellar roster of guest stars in past seasons. Who will we see return this time around?

Allison Janney is back for a two-episode arc. She’s now become this fascinating character, a '50s housewife facing the '60s and a serious transition as she’s unmoored from a traditional marriage. We have great hopes that we can bring her back for a lot, but we just have to juggle the fact that she’s on another show. Beau Bridges is now permanently back. We have a lovely cameo with Alex Borstein from Getting On. Josh Charles shows up in episode three, I believe. Sarah Silverman, Teddy Sears [return].

Are you concerned that viewers will become fatigued by how unlikeable Bill’s character still remains?

The writers and Michael felt strongly about an uncompromising quality [in Bill] that shows the affects of child abuse on a grown adult. He’s not only damaging to himself, but he is damaging to those around him. A sort of, “This is how it plays out.”

Also, the Bill Masters that met Virginia Johnson in 1956 is a very, very different man later in his life. He went through this remarkable transformation. So, if you’ve been tough enough to hang in with this character for this long, you’ll start to see him breaking that cycle of abuse this season. And that allows a certain freedom to settle in over the character — he’ll be much more human. What becomes clear is that there is a really kind man in there somewhere struggling to find his way to that person. He’s certainly much more relatable. You think, “There’s a guy who's really trying.” And that, I think, is a very winning character.

Masters of Sex airs Sundays at 10 p.m. on Showtime.