A growing number of biologists have discovered that girth and risky behavior are not wholly volitional but genetic. Recent understanding of human genetics has prompted a rethinking of how much control people have over who they are and how they act. It may be that genes influence whether an individual is fat, has a gift for dance, sports, politics, or addiction.

The familiar saying "it’s in the blood" has taken a scientific turn.

This also raises a number of ethical questions. Is the story of Cain and Abel, for example, the fate of mankind?

As Paul Rainbow, an anthropologist at Berkeley, puts it, "The older liberal world view that it’s all a question of will-power is still very present in America, but genetics has become a strong undercurrent" for behavioral differences.

In his book, "The Blank Slate," Steven Pinker, a psychologist at Harvard, confirmed that "we have now real evidence that some of the variation in personality is inherited."

This is liberating for people whose behavior is difficult to explain but guilt-raising for parents and grandparents. (This puts the burden on the "Old Adam").

On certain "problems," it will reduce the stigma of being fat (but this stigma is only fashionable).

What’s problematical, though, is the suspicion of some scientists that genes have something to do with violent and corrupt behavior. As Jeffrey M. Friedman, director of Starr Center for Human Genetics at Rockefeller University, asked, "If we find a murder mutation are we going to be more accepting of murderers, or are we going to lock them up even more tightly?"

In other words, would there be more tolerance or more bigotry, more permissiveness or more repression?

What do you do with cheaters, thieves, and murderers, who, instead of being accountable (which some people say is the "answer" to corruption), may say, "My genes made me do it!"

They may have inherited their disposition from their parents and grandparents.

That makes bad behavior biologically historical.