The DNA in our cells, which contains the genetic instructions that make us human, is passed on from parent to child along an unending line of generations. However, as recent experiments in mice have demonstrated, there is more to transgenerational inheritance than that. "Learned" experiences, which do not alter the underlying genetic material, can be passed on from one generation to the next - in mice, fruit flies, and possibly even humans. A new study ... has shown that such "epigenetic" memories can be passed down for 14 generations. This is the longest maintenance of transgenerational environmental memory observed in any animal to date. The researchers inserted a gene coding for fluorescent protein in [a species of] worms that, when activated, made them glow brightly under ultraviolet light. If the worms were kept at 20 degrees Celsius (68 degrees Fahrenheit), the array of transgenes was less active ... but when they were exposed to a warmer temperature of 25 degrees Celsius (77 degrees Fahrenheit), the activity of the transgenes was significantly increased. When these worms were moved back to the cooler temperature, their transgenes remained active - a sign that they were retaining the memory of their exposure to warmth. This high activity level was passed on for seven subsequent generations. Keeping worms at 25 degrees for five generations led to the transgene activity being maintained for at least 14 generations.