I think the "intro" portion being referred to is the sex, pregnancy, and giving birth parts of having a kid. A lot of adoptions happen at a young age after the child has been with a foster family for years. A lot of times adoption is more just a recognition of the facts on the ground

I understand where your coming from in regards to the demands on parenting. It's no easy task to be a good parent and it's common to see parents who do a shit job by doing the bare minimum. Where I disagree is with the need to show gratitude. My parents never asked for gratitude from me and I will never ask it from my two kids. Being a good parent is first and foremost a duty, going above and beyond as a parent is a part of that duty. You don't get a thank you for doing your job. That being said I always give gratitude where I can because I am truly grateful for people who do things for me. I regularly remind my parents that I'm grateful for what I am and that their love, hard work, and lessons made me the person I am today. I credit them for all of my successes.

Secondly it's evolutionarily beneficial for me to do my best for my kids so they can be the best people they can be. I don't expect gratitude for something that benefits me.

My wife and I regularly share our appreciation for the little things. I make it a point to try to thank her for anything I can because I know I miss so much.