Assertion [of "most marriages"] is reached by appropriate interpretation of "lack of knowledge about husband's profession".
Most wives would know name of husband's profession, but majority would not know more deeper things such as top 10 buzzwords.
BTW, I'm not saying that such lack of knowledge is necessarily bad -- specialization in life is an important thing.
Or for extra juice: "Our source, who requested to remain anonymous, wanted us to know that many democrats were concerned with the Obama admin's decision to..."