Cristline–
What’s “diverse”?
If a person is from an Irish, Swedish, Scot Presbyterian or whatever other light skinned kind of background, and it really means something to him & his family ---- they do Bobby Burns’ Day if they are of Scottish ancestry, or they play Irish music or compete in Irish step dancing if Irish, or just read up on their families’ history or whatever—that isn’t any less valid than being Hispanic or Vietnamese or some other group.
Your family does not know much about their history — so why don’t you sign up on ancestry.com and learn something! I know you mentioned 2 adoptions there, but not all the others were adopted.
Also, we adopted my second daughter. We only knew what her birth family had told about her ancestry – however, we were able to teach her about those heritages, take her to ethnic festivals, etc and when she got older, she began to study the language of one of her ancestries. It gave her back at least part of her “roots.”
If she ever wanted to write an essay using this as the topic, I think it would be interesting—of course it would depend on how well she wrote it, and what she said. And, it is up to her. But at least she has the option to do it.