Every year, thousands of adoptees looking for biological parents register with their state and private search registries. The search brings adoptees with a variety of motivation for seeking the people they're biologically related to. The most commonly cited reason is related to medical issues - they may have developed a disease that is commonly hereditary, for example. But, for the most part, it's undeniable that a majority of adoptees go looking for biological parents because they've developed a list of unanswerable questions as they've matured; Questions that maybe only their biological parents could answer.
If you're an adoptee looking for your birth parents, you can start by registering with your state's registry. Most likely, this registry will require mutual consent from both adoption parties before any contact information is released. Adoptees can also choose to search proactively. They can do so by registering online, where they'll be connected to a huge database of other people in the adoption community. They will need to look through profiles that are potential matches for their search and hope the person they're looking for is also registered and in the database. If working with a state registry isn't yielding any results, adoptees can petition to have a confidential intermediary granted access to their adoption file. From there, the C.I. can facilitate communication between the adoptive parties.
International adoptees may have a harder time tracking down their biological parents. However, there are search groups for international adoptees that work to help reunite overseas.