Looking For My Son Mathew

I am looking for my son Mathew. He was born Mercy Hospital in San Diego, CA on 8/10/1985 and was placed for adoption in 1989 from an agency in a Houston suburb. His full birthname is Mathew Ronald Howell. I believe the adoptive family kept his first name but changed his middle name and, obviously his last. I am also looking for my daughter Brittanie who was born on 7/17/1987 in Calais, Maine. She was placed for adoption at the same time Mathew was and went to the same family. If anyone has any information at all, I would greatly appreciate it. I pray every day that Mathew and Brittanie will look for me!