Mendel's laws underlie almost all of genetics. They state, for example, that it is the combination of dominant and recessive genes inherited from the parents that dictates an offspring's characteristics. In the main, this is true, but examples of inherited traits are being discovered that deviate from this rule. These "epigenetic" effects are caused not by genes themselves, but by inherited factors that affect gene expression in later generations. The latest such effect, described by a team led by Minoo Rassoulzadegan at Sophia Antipolis University in Nice, France, shows that RNA, as well as DNA, can carry information from one generation to another - a clear violation of the cherished notion of Mendelian inheritance.

Basically, mice that inherited dominant spotted tail genes had spotted tails, but some with normal tail genes had spotted tails - something that cannot happen according to DNA & gene inheritance laws. So it looks like that RNA can and does have some effect.

Source: New Scientist