Michelle Malkin is not Megan McArdle. All of their names begin with the letter "M" though.

McArdle also presents a false dichotomy between willpower and genes. Your genes presumably have a lot to do with your willpower (which is not to say that it's highly heritable, though in fact it may be). Perhaps she has not fully chucked the "ghost in the machine" and thinks willpower is the real, internal you as opposed to that genetic stuff from your parents.