Asa Butterfield and Gillian Anderson in Sex Education.

It stands to reason, or at least the logic of television plotting, that an extremely forthright sex therapist would raise an extremely uptight son. That’s the basis of Sex Education, a new Netflix comedy that stars Gillian Anderson as Jean, the therapist in question, and Asa Butterfield as her son Otis, who is so self-conscious he has trouble masturbating. The show hinges on Anderson and Butterfield’s parent-child dynamic, and together they deliver something that’s both awkward and sweetly human, especially once Otis decides to help out other high-school kids with the X-rated lessons he absorbed from his mom.

Ahead of Sex Education’s debut this Friday, Vulture sat down with the show’s two stars, who’ve developed a natural repartee of their own, trading thoughts on hair dye (Butterfield recently tried out platinum blond) before talking through their experiences on the show and the surprising things it taught them about sex. For Anderson, shooting Sex Education was a chance to preview what it might be like to have a son in high school, while for Butterfield, it gave him an opportunity to bring a little of his own geekiness to the screen. And, of course, also learn how to fake masturbate on camera.

Jean overshares about sex with Otis, which makes him uncomfortable and defines their relationship. How did you develop that sort of awkward dynamic?
Asa Butterfield: It came quite naturally, I think. They are very funny, very touching, very honest conversations that a mother and son would have.

Gillian Anderson: It did come naturally. I have two younger boys who haven’t got to that stage yet. Early on, I suddenly realized, Hang on, I’m observing something that I’m about to go through. When we were doing scenes, I would go, Oh my God, that’s to come.

Did you research the real-life practice of sex therapy at all?
Asa Butterfield: My mom is a psychologist in the real world, so we spoke about it leading up to it. She was reading the script and, yeah, it’s fascinating how much impact you can have on someone when they’re in their most vulnerable state. The sensitivity of it was something I found quite interesting.

Gillian Anderson: In my experience — I’ve been in therapy for years and have played therapists before — it was trying to find the way in that was different from what I did before. And to celebrate as much as possible the opportunity to do comedy.

The show toes a line between being explicit about sex and talking about it without leering. How did you approach that as actors?
Gillian Anderson: My character doesn’t have a lot of sex scenes, so I feel like how she approaches sex in conversation — even if it may be somewhat inappropriate in terms of who it is that she’s having a conversation with — it’s still very focused and there’s a motivation behind it. It’s not fortuitous.

Asa Butterfield: Similarly, I don’t have any extreme sex scenes, so I didn’t have any firsthand sense of that. But in speaking to the guys who did do more of the “sexy time,” everyone is as comfortable as they could be doing things like that, which often isn’t very comfortable.

I thought Jean’s house was hilarious. It’s full of condoms, shrines, and all sorts of weird sex things.
Gillian Anderson: I discovered a new penis every day while we were filming. I mean, even in the bathroom …

Asa Butterfield: Surrounding the sink!

Gillian Anderson: … there was a chess set of penises and vaginas of various sizes and shapes.

Asa Butterfield: All different sizes.

Gillian, you said you wanted to do more comedy and make Jean different from therapists you’d played before. Was there anything specific you wanted to bring out in her?
Gillian Anderson: It was important to me that she felt like a woman who was of my age. She’s been written by a young woman and it was important to me that there was enough of a mature woman’s experience in there. I’m speaking from my own experience of neurosis, et cetera, et cetera. That showed up — the little things, the hormonal things and the mood things — which may or may not be obvious in the final cut.

Asa, what parts of Otis did you bring to the character?
Asa Butterfield: I’m quite geeky. He’s into his video games, as am I. All the games he plays are the games I play, so it did feel very close to home. There are a lot of references in there which I’ve snuck in.

Which games?
Asa Butterfield: He’s a big Nintendo fan, as I am. We got a Nintendo to give us a prop, and so it ended up in my front room.

Gillian Anderson: None of the penises on set are mine.

Laurie Nunn wrote the series, and it’s her first TV show. We’re used to seeing a lot of sex comedies from a male perspective, did you feel like hers moved the show in a different direction than you might expect?
Gillian Anderson: I definitely feel it in terms of the way that the female characters are written. It feels like they’ve been written by a female. Subtleties and sensitivities. Also, the ways the sex scenes are handled and the lesbian relationship, it feels like it’s handled with care. Not that it wouldn’t be handled with care if written by a man, but it feels sensitive and it doesn’t feel gratuitous.

What’s it like to work with Ben Taylor as a director? He’s also the director for Catastrophe, another comedy that doesn’t necessarily draw attention to itself with hard jokes.
Asa Butterfield: Ben helped me find elements of Otis’s character which ended up being trademark to him, like often he just blurts out things when there’s awkward silence or he doesn’t know what to say. That was something that was written in, but in talking to Ben about it, it became more.

Gillian Anderson: John Hughes films were hugely important in his younger life, and so this is very much an ode to that. I think, because of that, he was so confident in what he was creating that it allowed the actors to relax into the essence of what he wanted the show to be. There’s no hang-up, there’s no stigma, that’s not at any point what the show is about. It’s about blasting through the stigma so that the conversation of sex can be had with a level of freedom and openness that it really should in 2018.

Asa Butterfield: Quite often, he gets someone to come up on set and just start dancing. Just to add a sort of relaxedness and spontaneity to it.

Gillian Anderson: He never did that in my scenes.

Asa Butterfield: I remember two occasions of dancing people.

Gillian Anderson: That’s just like Fortnite.

Asa Butterfield: What’s like Fortnite? The Fortnite dances?

Gillian Anderson: Yeah, all the Fortnite dances.

I’m very impressed that you know about Fortnite.
Asa Butterfield: Me too.

Gillian Anderson: Oh my God, I’ve got two little boys. I wish I didn’t know about Fortnite.

Asa, what was it like to film those masturbation scenes?
Asa Butterfield: It was actually a lot of fun. It’s a bit weird, some of them were more fun than others because I’ve got three wanking scenes. Only one of them is successful. Two of them have these very clever little camera tricks, so not only was it me pretending to masturbate, but we’ve got this whole rig. It’s fucking weird pretending to wank with a whole group of people there.

Gillian Anderson: I’m so glad it wasn’t me.

Asa Butterfield: Trying to avoid eye contact with anyone, and the whole crew is trying to avoid contact with me.

Gillian Anderson [to Asa]: But you were so cool about the whole thing.

Asa Butterfield: I think Otis’s difficulty with it actually made it easier. He’s not an expert at it, so it doesn’t have to look perfect.

Where did you film the show? It’s set in an idyllic, small-town world.
Asa Butterfield: In Wales, around Cardiff and Newport. We had two beautiful roads that wound down through the hills, through the valley.

Gillian Anderson: I think Ben very much enjoys the fact that it is Everywhere-ville, the fact that it feels both British and American, that we kind of have ‘80ish clothes and yet there’s smartphones. He enjoys the ambiguity of that.

I don’t know how different British high school is, but it did feel very much like a prototypical American high-school setting.
Asa Butterfield: It didn’t feel like a British school. It didn’t feel like the one I went to. I think a lot of British schools aren’t like that, with the lockers and there’s no uniform. Everyone’s got a bit more personality in school, whereas back in the U.K., it’s ground down until everyone’s the same.

For teenagers who might not get great sex education in school, it feels like this show could help. Do you feel a responsibility to provide good information with it?
Gillian Anderson: When we were doing international press, there were three different Polish journalists who basically told us that there is no sex education in Poland, and so therefore this show and our work was their sex education, and that it was our responsibility to educate.

Did the show either of you anything about sex you hadn’t known?
Asa Butterfield: For me, vaginismus and various uses of cranberry juice.

Gillian Anderson: Scrotal anxiety. I didn’t realize that scrotal anxiety could happen.

Asa Butterfield: What is scrotal anxiety?

Gillian Anderson: Scrotal anxiety is, if I’m correct in remembering, such a profound fear of being able to ejaculate. It has to do with the scrotum, that your testicles might even disappear.

Asa Butterfield: Like, seize up?

Gillian Anderson: Seize up and go inside your body. I may have made that entirely up, I don’t know.

Gillian Anderson and Asa Butterfield on Sex Education