When Jagged Edge first formed in their teens, the members realized the sum of their group would be greater than its individual parts — an understanding that has been the main ingredient of their success for nearly three decades.

One of the most iconic groups of modern R&B, Jagged Edge — Richard Wingo, Kyle Norman and lead singers (and identical twins) Brian and Brandon Casey — is back with its 11th studio album, “All Original Parts: Vol. 1.” The title of the 15-track project out now points to the group’s solidarity: They’ve never broken up or switched original members.

“The love is actually genuinely real. We really care about each other’s well- being,” Wingo said. “I guess a lot of groups, they really didn’t have that. Love will keep you together.”

The artists say “Vol. 1” is the first of three they plan to release this year. But the men behind classic songs like “Promise” and “He Can’t Love You” say while the sonics and even subject matter of R&B have changed since their first hit single in 1997, they’re still committed to telling stories about romance and relationships.

“It’s almost like love ain’t cool no more. Well, I don’t believe that. We don’t feel like that,” said Brian Casey. “Love is always going to be cool.”

The group’s 1999 song “Let’s Get Married” is still nearly impossible to avoid at weddings — the original, a ceremony mainstay, and the remix, packing dance floors during receptions.

This interview with Brian and Brandon Casey has been edited for clarity and length.

Q: Most groups seem to break up at some point. What has allowed you to stay together?

Brian Casey: That’s the benefit of us being actually four guys who really mesh with each other. … We’ll split a couple dollars here and there when we got to, to keep this together. We’ll take the hits to keep giving the fans what they said they fell in love with. … What we’re able to do in turn is worth that split. It’s worth that sacrifice.

Q: R&B has drastically changed since you came on the scene. How have you navigated the changes?

Brandon Casey: Number one: Staying true to Jagged Edge. That’s the first thing because that’s the vehicle, right? So, we never want to go too far from what our fans love us from. But we’re actually musicians, so it’s hard to just stay in one little place. … Our sound is as eclectic as it’s ever been.

Q: When you look over the longevity of your career, your love songs are timeless. What do you remember about first entering the industry?

Brian: We came up in an era of “Bump n’ Grind,” “Freek’n You” and “Freak Me” … So, we knew it would be a conscious decision for us to be the age that we were making songs talking about things like getting married. But we’ve never been afraid of that challenge, number one. So, I think of that. But I also think of how taking that route allowed us to be in the same room with some of our heroes who now looked at us as peers. And that was meeting Luther Vandross, meeting Prince, and them having positive things to say about our music.

Q: Do you all feel you get the credit and recognition you deserve?

Brandon: We get asked things like that a lot. So, I guess it starts to make us think, “Do we?” It’s been such a layered experience, right? It’s so many things to be proud of. We don’t have nothing that we’ve built without our fans. And for us, that’s the most important, most heartwarming, gratifying thing, that it’s somebody who loves you for what you do. … We’re one of the few groups who get onstage and them girls scream like we’re taking our clothes off, and we never take no clothes off. They scream like we got routines — we don’t do none of that, right? We always come in the arena like, “This is just us. This is who we are.” And they love us for that. And it’s no feeling that is even close.

Q: Do you understand the impact your songs have had on fans and music?

Brian: I don’t know that you can ever understand it while you’re still in the middle of it. … But I will say, when you meet certain people, it’s heartwarming, and it gives you a sense of what that impact is, you know what I mean? And it’s not until you get to talk to people who are looking at it from the outside-in that you realize, “Man, we did an all right job.”