I am not adopted, but my siblings both are.
I think I would try to talk to your parents about this first. I totally understand your feelings on the matter, but I think you should be open with your adoptive parents. Let them know that you love them and will always think of them as your parents, but you also want to know about your biological parents. They may be able to share additional information about your adoption that you do not have access to. They may also have an idea of where to get more information. I understand your want to learn more about your biological parents, but I would not keep this a secret from your adoptive parents. I think it would hurt them more when they find out that you have been searching without their knowledge.
I am not sure how your parents view adoption, but many current domestic adoptions are open adoptions. The point of view is that a child can’t receive too much love and that it is healthy for children to know more about their biological parents. Hopefully your adoptive parents won’t be offended with your want to know more about your biological parents.
Also, I love this adoption poem, so I thought I would share 🙂
Once there were two women who never knew each other.
One you do not remember, the other you call Mother.
Two different lives shaped to make you one.
One became your guiding star, the other became your sun.
The first one gave you life, and the second taught you to live it.
The first gave you a need for love. The second was there to give it.
One gave you a nationality. The other gave you a name.
One gave you a talent. The other gave you aim.
One gave you emotions. The other calmed your fears.
One saw your first sweet smile. The other dried your tears.
One sought for you a home that she could not provide.
The other prayed for a child and her hope was not denied.
And now you ask me, through your tears,
the age-old question unanswered through the years.
Heredity or environment, which are you a product of?
Neither, my darling. Neither. Just two different kinds of Love.