Using the Lamarckian theory, one can argue that a child born to an obese parent, will too be obese. They have genetically acquired the trait for obesity and overeating from their parent as opposed to their conscious decision as a child. Likewise, a child born to an average or fit parent, will be fit or average body weight as they have inherited the characteristic for a fit body from their parent. And, if a parent is obese with the birth of the first child, they should expect an obese child and if the parent loses the weight with the birth of second child, then that child will not be expected to be overweight. So, the traits are interchangeable, and not permanent. The species may begin as one trait, and through conscious decisions, make adaptations which may better or worsen the future of generations to come.
The thing with both Lamarckism and Darwinism, their is no end. There is no way to know how a civilization will conclude, but unless the people of the United States find their wake up call, it seems as though many will find a growing in the girths of civilians. The numbers for obesity will continue to rise, and more individuals will lose to a fight of gluttony and over indulging. America needs a wake up call, and the change may start with