1. They would get no argument from me. It was much better to adopt those children than to have them in foster care with no family. Those children had no shot at the "ideal" and it sounds like your family has given them a good home. Overall stats don't always bear out in individual circumstances. Read that again if need be because I won't address it again.
2. The divorce rate is not 50% anymore, unless you have ALREADY been divorced, in which case the home is "broken up" in any case. And note I did not say "children do best in a two parent household". No. Children do best in the home of their MARRIED, BIOLOGICAL PARENTS.
Nearly three decades of research evaluating the impact of family structure on the health and well-being of children demonstrates that children living with their married, biological parents consistently have better physical, emotional, and academic ...
www.ncbi.nlm.nih.gov
What exactly is the advantage of being raised by parents who are married rather than divorces parents? It’s complicated.
www.fatherly.com
3. See #1. "Overall stats, individual circumstances", etc.