MENDELIAN inheritance, the central tenet of genetics, is under attack from a few scrawny weeds that haven’t read the textbooks. The weeds are somehow inheriting DNA sequences from their grandparents that neither of their parents possessed – which is supposed to be impossible.
The orthodox view is that genes are passed down in the form of DNA, and all organisms have to make do with this parental DNA inheritance, mutations and all. Chemical or structural modifications to DNA can switch off genes, and these changes can pass from generation to generation, a phenomenon called epigenesis. But epigenetic changes do not alter…
