Adoptions of children in the 60's and 70's was different, I understand that a lot of adoptive parents were instructed to raise the children to be just like the family, in other words, to deny the cultural heritage.
Even in a closed domestic adoption, most adoptive parents now do try to honor adoptive children's heritage and educate and expose them to their culture in a variety of manners. I think this is a real pendulum swing so I agree that it's comparing different situation.
And on a side note, my husband was a domestic transracial adoptee and very well adjusted
