Michael Kennedy, 36-year-old son of the late Sen. Robert F. Kennedy, has checked into an alcohol rehabilitation center. In a press release issued Monday through the Citizen's Energy Corp., the nonprofit utility company he heads in Boston, Kennedy said, "I have come to recognize I had a dependence on alcohol. I am currently participating in a program and I am committed to completing it this month." Reports are that Kennedy checked into a clinic on Jan. 22, the day before his grandmother, Rose Kennedy, died. He was listed as an usher at her funeral but was absent.