I've been thinking on this for awhile. My partner and I have been together 8 years, with a kid apiece. No subsequent 'ours' children and he had a vasectomy so there never will be. My son is 11 and my stepdaughter is 9.

I'd say it's been a success. We have close bonds with each other's kids and the kids are close to each other as well. I'm at least a little proud of us for making it work so well. It feels natural, even though we don't quite fill a parental role in our children's lives. It's closer to a loving aunt/uncle relationship with their niece/nephew.

I've been pondering on what goes into us being a happy family, and my theory comes down to a few factors.

Timing- Our kids were very young when we got together. They don't remember us being with their other parent, they only remember us being a couple. So there's no sense of the upset of the status quo, no feeling that we are replacing a role the other parent once held. For my part, I have known my stepdaughter at basically every stage of her life so far. I think that's meaningful. I got the chance to care for her as a toddler, which involved holding her in my arms, kissing boo-boos and all that so physical affection has always been easy. I got to see her become a whole-ass person, and take part in the formation of that personhood. I think that makes the relationship easier than had I been introduced to her, say, at the age she is now.

Luck- One thing I like about us as a family is that we all have aspects of ourselves that fit into each other. Like my son and stepdaughter like to make up crazy pretend games and challenges together. My stepdaughter and I like to do arts and crafts and do 'girly' things like hair dye parties, manicure night and 'fancy' tea parties together. My s/o and my son like to talk in-depth about nerdy stuff like Star Wars, LotR and video games, and they play together a lot too. What I'm saying is that we have a good combination of personalities and similar interests, and I think we lucked out in that regard.

Experience- My father figure is not related to me by blood, but he treats me like his own daughter. Therefore the concept of loving a child that was not my own was something I was very open to and understood on a fundamental level. My bond with my son is different than it is with my SD, but I've never felt disproportionately annoyed, frustrated or angry with my SD's actions compared to my son's because she isn't mine biologically, which is a trend I see a lot of step parents struggling with.

I'm curious to hear your guys' thoughts about what factors go into happy and healthy blended families.