Canary mothers have been found to encrypt chemical messages within their eggs informing their little chick-to-be about what to expect of life post shell. In response to their mother's message, the chick will then develop accordingly and after they hatch will beg at acceptable levels relevant to their parents socio-econmic status so to speak. In other words, chick informed that they are growing up in a good environment grow bigger and demand more food then chicks told otherwise. Perhaps some relevance to America's childhood obesity problem. You gotta love epigenetic inheritance.