there have many studies on how environment affects ones's personality versus genetics. you may wish to google this and see what u might find out. it may enlighten you on your inquiry. new england medical journal is a great place to start in your google to see the results of studies on adopted persons and the results of those studies. both environment and genetics contribute to who one is/becomes.
i hope this helps you. i'm not adopted but know ppl who are as i stated in a previous post. sometimes researching studies will help you find answers. having a therapist also helps many adoptees better understand their behaviors and feelings, too.
as "ihateit" stated we are here to support you in ways we can. perhaps another adoptee will see your post and reply. give a little time to see what happens. some days more people are active at the site than others. i wish you well and hope you can find some resolution to your questions.