Neil Patrick Harris and fiancé David Burtka let Oprah Winfrey into their home to meet their twins, Gideon and Harper, who the couple revealed were born via surrogate. (Check out footage from the interview below).

The How I Met Your Mother star and his fiancé Burtka sat down with Oprah for an interview in their Los Angeles home, which will air Sunday night at 9 p.m. EDT on Oprah's Next Chapter on OWN. The notoriously reclusive Harris has been successful in keeping his personal and public lives separate, so Oprah's interview sheds some light on old news, such as the couple's decision to have children, and the twins' conception.

I think the way they were brought into this world was very unique and weirdly scientific, and the technology involved in it, I think, is remarkable, Harris says. But it came because we really, really wanted kids. Like we really had thought it through financially, emotionally, relationship-wise. Like we didn't just accidentally get pregnant and decide that now we need to make this work. These kids came into our world with nothing but love.

Harris and Burtka also explained the surrogate/donor situation that led to twins -- made from two eggs, with Harris and Burtka each fertilizing one -- then being implanted in the surrogate.

Two eggs, two embryos, one of mine, one of his, is how Burtka explained it.

Harris said they did not know the egg donor, but did research her medical and personal history. But the duo did meet the surrogate. Oprah noted a surrogate who also wasn't a donor seemed unusual.

She was more like the oven, Burtka said.

The resulting twins, Gideon and Harper Grace, showed off their personalities during the interview: the former being a bit bashful; the latter more gregarious. Burtka said the two toddlers enjoy the water and were taking swimming lessons ahead of the summer.

Harris also opened up about his sexuality, saying he knew he was gay from an early age, around six or seven, but was confused by his feelings. He tried to date girls as a teenager like his friends.

I did feel like it wasn't clicking like it was supposed to, and kept wondering, was it me?

Check out video from the interview below.

Oprah meets Gideon and Harper, Neil Patrick Harris and David Burtka's adorable twins, in the backyard of their California home. Find out how two eggs, two embryos, one anonymous egg donor and one surrogate mother produced these happy, healthy children.

 Tune in Sunday, June 3, at 9/8c for more from Neil Patrick Harris and David Burtka!