I suspect that the day she has unmonitored internet access she will find out the truth herself. I’m an adoptee and I grew-up knowing that my white brother cost my parents $30,000 (I was around $12,000 in 1976) and I could have had a sibling 10 years earlier and for practically free to my parents, if it weren’t for their prejudice against skin color.
I think there are worse questions lurking in the wildly imaginative mind of an adoptee… ‘Am I a product of rape?”, “Is my mother a total head case?”, “Was I stolen and sold in the black market?”, “Is my mother a pirate and my sister Kate Winslet?” The truth tends to be much more boring and I’ve always found it helpful to fill in the details.
I think this kind of question will be dated soon. Sort of like, if we don’t tell them about sex maybe they won’t have any. We will go into your closet and dig up decades old receipts while you’re at grandma’s house. Don’t doubt it for a minute. 
