The International Movie Database has this info on Kelsey Grammar: "His father was murdered, in 1968, in the Virgin Islands. His sister, Karen Elisa Grammer, was murdered, in 1975, while finishing a shift working at a Red Lobster in Colorado Springs, Colorado. Had two stepbrothers (from his father's second marriage) that were killed in a shark/scuba accident."
You mentioned his sister. Are the other deaths factual?
After all those deaths, I think he was raised by his grandfather, a military man. Probably why he leans right politically.