Tying in with my conference paper and post last week on the The Classing and Gendering of Self-Presentation here's a good passage by Engels to illustrate this point further.
We are confronted with this new form of family in all its severity among the Greeks. As Marx noted the position of the goddesses in mythology represents an earlier period, when women still occupied a freer and more respected place, in the Heroic Age, we could fine women degraded owing to the predominance of the man and the competition of female slaves...The modern conjugal family is based on...admitted or masked domestic slavery of women, and modern society is a mass made up exclusively of conjugal families, like so many molecules. In this day and age, man in the great majority of cases, must support and nourish the family, at least in the propertied classes; and this gives him a sovereign authority which does not need legal privilege to back it up. Within the family man is the bourgeois; woman plays the part of proletariat. But in the industrialist sphere, the specific character of economic oppression that weighs on the proletariat is only manifest in all its severity after all the legal privileges of the capitalist class have been suppressed and complete legal equality of the two classes has been established; the democratic republic does not suppress the antagonism between the two classes, the contrary is true: that is what, first of all, provides the ground where the struggle is going to be resolved.