All the supposing is finished,"" claims an adoptee, when describing his successful and stubborn search for his birth mother. Another successful searcher, married and with children of her own, nevertheless exults: ""I now have a brother and a sister. I'm not an only child anymore."" The triangle of the title lasts a lifetime, often making the adult adoptee feel like ""the perennial child"" as well as ""the anonymous child."" The question raised by this book and by a growing number of adoptee activists is, Why all that secrecy? Why sealed records and close-lipped agencies and adoptive parents, even when adoptees become adults? This is the report of a study that covered the entire US and Canada and took in the adoptee, the adoptive parents, and the birth parents--including birth fathers, who are often ignored even in the sealed records. The book supplies a historical and international overview of adoption practices and lists the study's statistics. But the bulk is devoted to excerpts of the accounts acquired from those adopted, adopting, searching, or being found. Since follow-ups on birth parents have been virtually non-existent, this is something of a first. (Betty Jean Lifton's Born Twice is a more detailed version of the many tales told here.) The message is that breaking the seal can profit everyone. It does not tend to Change life patterns drastically. Yet it can fill in missing genetic and cultural information; fears of rejection and long-held fantasies can finally dissolve. The authors advocate change and refer often to adoptee activist groups, but the book is, for all that, a mild-mannered work, sympathetically offering its findings in the interest of those who stand at any point of the triangle.