Christine, who reunited with her two half brothers as an adult, spoke on NPR about taking the first step. They were all a little bit shy about it, she said, thinking that after all of these years the other siblings might not reciprocate their interest. Once they started hanging out, it was “a joy” to have more siblings, she said. Start with an email or phone call, and then invite him or her to meet for something low-key, like coffee.

Full siblings who grew up together have had years to negotiate boundaries and get to know each other, but you and your sibling just met as adults. Though you may have an idealistic portrait of what it will be like to have a brother or sister who understands and supports you, it may not happen immediately. Treat bonding with your long-lost sibling like starting a new friendship: meet up occasionally in low pressure situations, and reveal information slowly. Don’t overwhelm the new sibling by forcing large family interactions unless they express an interest in attending an extended family function.

Often, divorce, foster care or adoption separates siblings. In childhood, the court system or the children's parents may or may not have given siblings the legal right to contact each other. As mutually consenting adults, you and your sibling can reunite. However, if your sibling does not consent to reconnecting with you, and won’t return phone calls or letters, you can’t force it. As much as rejection hurts, your sibling has a legal right to his or her privacy, says Cynthia Mabry, professor of adoptive and family law at Howard University.

If you are aware of a long-lost sibling with whom you have not yet reconnected, there are resources for finding your brother or sister. Some callers on Talk of the Nation had reconnected with their siblings through genealogy websites or requests posted on the Internet. The international organization Camp To Belong reconnects siblings placed in separate foster care families. If the adoption laws in your state prevent you from finding out more about your birth family, you can also lobby to have them changed, as a congresswoman from Maine did successfully.