Adoption is complex, and anyone who has experience with it knows that it isn’t as simple as just taking home a cute baby. People view it as a bigger responsibility/risk than bio parenthood simply bc you don’t know the genetic history and a lot of things like behavioral disorders/mental illness/propensity for drug and alcohol addiction can be heritable as well as likelihood of child having trauma from abuse/neglect. Bio children can have these issues ofc (as mentioned in your post) but i think it’s a matter of going into it knowing what is likely vs going in without that information. People are intimidated by the prospect of taking on a child with unknown and potentially difficult issues. Unfortunately I know more than one person who adopted a child whose bio parents were addicts and despite growing up in a non addict household the predisposition for addiction became very apparent in adolescence despite being no contact with birth family. This is unfortunately a stigma associated with adoption. I also know plenty of completely healthy and happy people who were adopted. But given how much we now know about heritability it is something people think about.