Limited forms of Lamarkian inheritance, such as in the operation of metabolism, seem to be a reality, passed down through generations by epigenetic modifications. Here is a popular science article on the topic: researchers "described a series of experiments that caused nematodes raised under the same environmental conditions to experience dramatically different lifespans. Some individuals were exceptionally long-lived, and their descendants, through three generations, also enjoyed long lives. Clearly, the longevity advantage was inherited. And yet, the worms, both short- and long-lived, were genetically identical. This type of finding - an inherited difference that cannot be explained by variations in genes themselves - has become increasingly common, in part because scientists now know that genes are not the only authors of inheritance. There are ghostwriters, too. At first glance, these scribes seem quite ordinary - methyl, acetyl, and phosphoryl groups, clinging to proteins associated with DNA, or sometimes even to DNA itself. ... There is increasing evidence that epigenetic modifications are transgenerational (inherited through multiple generations) in a variety of species. Examples include coat color in mammals, eye color in Drosophila, symmetry in flowers, and now longevity in C. elegans. ... There seems to be a renewed acceptance for the Lamarckian concept (in limited cases). This could change our understanding of inheritance in that it would add another component, probably minor, but present, in addition to Mendelian genetics."