With so little information, there isn't anyway to look up his Purpua family and know I've found the correct one.
You probably know the adoption records (where you'll find his original birth certificate with his biological parents names) are confidential & under court seal.
Birth parents or biological siblings can register with the Adoption Information Registory, New York State Dept. Health, www.health.ny.gov/vital_records/adoption.htm
There is also a good article "Finding Your Birth Family with DNA", FAmilyTree Magazine, 12/17. Successful Searching!