Firstly "that doesn't mean the upbringing will be as healthy" <--- based on what grounds? Why does a child need a father and a mother? It seems that only thing that child truly needs are loving parents like countless studies have shown. Please provide some back up for your arguments.
What does this mean? That's how it has always been, that's how it was established since whoever the first parents were, that's how it has worked for millenia. A father, a mother, and a child. The upbringing won't be as healthy because by default, a mother and a father is better than two mothers or two fathers (assuming they're equally as good parents), and I already explained why, something that you didn't address. But of course, 2015 came, gay marriages were legalized, and now everyone thinks it's all hip and modern to give whatever rights they can think of to gay people. If you had the choice, would you really give a child to a gay couple rather than a hetero one, provided you're convinced both of them are fit for parenting? A child needs two different viewpoints in his life to create a basic understanding of the world and the two genders that inhabit it and with which he or she is going to interact with for all his/her life, until it grows old enough to perfect his views on his own.
This isn't about which one is better. It's about the fact that gay parents and hetero parents should have equal rights to apply for adopting a child.
Ah, yes. The infamous equal rights. If that's all the thread asks then sure - if they're fit for parenting, gay couples shouldn't be disallowed from adopting children.
The point I'm trying to bring across is different: from two equally good at parenting couples, the hetero one would and should be preferred.
Giving gays adopting rights isn't going to change the criteria for adopting parents. The process won't change. Ofcourse always the potentially best parents will get picked.
Okay, and when did I deny any of this?