McIntyre was born in Needham, Massachusetts. His parents were Thomas McIntyre, a union official, and his wife Katherine (neé Bowen) a community theater Actress. His mother died on November 30, 2014, after a long battle with Alzheimer's. He is the youngest of nine children with older siblings, Judy, Alice, Susan, Tricia, Carol, Jean, Kate, and Tommy, in an Irish-American Catholic family. McIntyre graduated from Catholic Memorial School in West Roxbury, Massachusetts, an all-male Catholic private school. He shares the same birth date as his sister, Carol. Another sister, Judy, is an Actress.