In Massachusetts, identifying information may be released to an adult adoptee (age 21) and to birth parents if a placement agency has received written permission from both the adoptee and birth parent.

An adoptee under the age of 18 may receive identifying information if he or she has the written permission of the adoptive parents. Non-identifying information concerning medical, ethnic, socio-economic, and educational circumstances is available upon the request of adoptees (age 18), birth parent(s), and adoptive parents if the adoptee is younger than 18. The placement agency may also, at its discretion, release non-identifying information concerning the circumstances under which the adoptee was placed for adoption. 
Mass. Gen. Laws Ann. ch. 210 5D.