In Kusior v. Silver (1960) 54 Cal.2d 603, it was argued that there was no longer a reasonable relationship between the presumption and the fact sought to be presumed. In reply to this argument, our Supreme Court said: "There are significant reasons why the integrity of the family when husband and wife are living together as such should not be impugned. A conclusive presumption is in actuality a substantive rule of law and cannot be said to be unconstitutional unless it transcends such a power of the Legislature." ( Id., at p. 619.)