Name a Catholic that views Genesis as symbolic??? You have NO idea of what you are talking about.
There must have been a helluva lot of incest for the first few generations after Adam and Eve.
CCC 337 God himself created the visible world in all its richness, diversity and order. Scripture presents the work of the Creator symbolically as a succession of six days of divine "work", concluded by the "rest" of the seventh day.
http://www.vatican.va/archive/ccc_css/archive/catechism/p1s2c1p5.htm