Henri - you raise a very important point about the kids right to find their biological parents later in life.
I have some relatively direct experience with this thanks to the barbarism of the Catholic Church in Ireland, who 'accidentally' lost a whole bunch of adoption records, including those of an old college friend of mine. The urge to find your real biological parents is real, and it is both emotional and highly practical. How many times have you been asked "do you have a family history of X medical condition"? Not knowing who your real family are makes it harder for your doctor to give you the best possible care. If for no other reason than the child's health, ever adopted child should have the right to find out at least some important information about their biological parents.
To me the only issue with gay adoption are the issues with adoption in general. The science is in, kids who grow up in a gay family are no worse off than other kids.
As for how acceptable it is/will be. Time will take care of that. Once a generation of kids grows up knowing kids with two mommies or two daddies from childhood onwards, it will simply cease to be 'a thing'.
Obviously, it will take a VERY long time for global acceptance, since big swaths of the world are still stuck in the middle ages when it comes to human rights!
B.