The Swintons are a distinguished old Scottish family. I heard that you guys have been living in the same home for over 1,000 years.

We don’t live in a cave, but yes, the family has lived there since 876, though the bricks and mortar have dwindled and perished and been rebuilt since then. This particular house was built around 1830. It’s a gray stone Scottish baronial house, and it’s got little turrets. It’s hideous, if you must know. Absolutely hideous. I say that with love.

Didn’t you plot to murder your infant brother in that house?
Yes, there was a bungled attempt to kill my brother when I was 4½. I assume it happens all the time. It was to do with the fact that I wanted a sister, and I had a third brother, and at 4½, that really felt like the sky was falling in. I just went in and looked at him. I don’t think I had anything particular planned.

But you walked into the nursery and discovered that he was already choking on something.
Yeah, and I then immediately started to pull this ribbon out of his mouth and was hailed as his savior. It was a good call.

It seems as if most articles use the word “androgynous” to describe you, because you’ve been able to go back and forth between sexes in your work. Were you a tomboy growing up?
I was everything. I wasn’t only interested in one thing. I wore boys’ clothes just as much as I wore girls’ clothes, but that didn’t mean I only wore boys’ clothes. There’s only so much you can do when you look the way I do.

I read that you donned a prosthesis for your one-woman show “Man to Man,” in which you played both husband and wife.
Actually it was a balled pair of socks, but the idea of it morphing in legend into a penis prosthetic is fantastic, and we should leave it right there.

In your film, “We Need To Talk About Kevin,” we watch you raise a future mass murderer. It’s an amazing piece of birth control.
It’s a fantasy that has as much to do with the practical business of bringing up a child as “Rosemary’s Baby” has to do with being pregnant. Still, there’s always going to be a moment in a pregnancy when you wonder whether the devil was involved.

Was there a point when you hated your twins?
No, because I lucked out in the chemical-reaction department, but I know people who have and who can never talk about it with anybody. I have witnessed the unsayable shame of feeling that they are not in love with their babies. No amount of other people saying, “She’s adorable,” is going to make it any better.

You once admitted that you enjoy leaving your kids to travel for work. That’s unusual to hear.
Absolutely. When mothers say that they really can’t bear to be away from their children, what they’re really doing is protesting a little too much, and what they would really love to have is a night in a hotel room lying diagonally across the bed and eating all sorts of food.

A few years ago, the tabloids suggested that you were enjoying a very exotic sex life, having the father of your children, John Byrne, at home and traveling the world with Sandro Kopp, your younger lover.
The ménage à trois. Apparently people are supposed to deem themselves famous enough to hold a press conference and tell the world about their relationships. We made the terrible error of not doing that, and so natural transitions in our family got missed.

So this odd arrangement never existed, with your older partner happily carrying the bags of the young lover into the family home?
No. John lives with his girlfriend in Edinburgh and has for like five years. He happened to pick us up from the airport, because he had been looking after the kids while we were in London. There’s no drama. The most transgressive thing that we have done is not be acrimonious.

People were hoping for more, you know: switching bedrooms depending on the day, that kind of thing.
Isn’t there a big television show in America like that? “Big Love”? I’m too dull for Mormonism, but everyone is welcome to have whatever fantasies they like.

Interview by Andrew Goldman.

Portrait by Douglas Neill.