My little sister is adopted. She is 2.5 years younger than me and was 2 weeks old when we got her.
My parents have told her right from the beginning that she was adopted. But they told her that they wanted another little girl and wanted her so badly that they chose her to join their family.
(I can't remember everything that they told her.)

She grew up feeling loved, and really had little desire to find out about her birth family. She knew who her family was. Us.
Much later in her adult life (late 30's) she finally registered in case anybody in her birth family had been looking for her, and found out that they and finally met them. Turned out that her birth parents had ended up marrying and having more chidlren (full biological sisters for her.)
She enjoyed meeting them but told them that my parents are her parents.

Thanks for sharing your story.