Mac was married to New York City native Claire Conrad. They married not long before Mac's father died, presumably during the late 1980s and the couple had no children, though Claire had a child named Reed Garrett from a previous relationship, whom she had since put up for adoption. Mac once described Claire as 5'6", athletic, with light brown hair and big blue eyes. Claire was killed in the September 11 attacks and her death troubles and pains him to this day, causing chronic insomnia. After her death, Mac got rid of everything that reminded him of her, except pictures and a beach ball she had blown up, saying, "Her breath is still in there." Her remains were never recovered from the debris of the World Trade Center.