Rock Doc

Like millions of Americans, my day starts by plugging in the coffeepot. In my case, it’s an old fashion percolator. It clears its throat and brews my coffee while I rub sleep out of my eyes and brush my teeth.

My habit of starting my day with coffee -- and following that initial cup with doses of java in the mid-morning, the late morning and the early-afternoon -- may be at least partially grounded in my genes.

Researchers have long believed that genetics influences a person’s daily coffee consumption. Early this fall, a new study fleshed out just how many variations in genes may be involved i...