avhaben – aside from the fact that in botei kvaros across Europe Rabonnim are buried with wives and daughters above below or beside them, If you have any knowledge of burial practices in eretz yisroel before and after the churban bayis sheini, you would know that families buried their meisim in ossuaries for a few years, then reinterred the bones. These were buried in family tombs, of which there are dozens around yerushalayim, especially in the areas of sanhedriya and talpiyot. families were buried together.
At some point in the last 200 years a determination was made in some communities that it was appropriate to bury men and women separately if the space was available, but there is an abundance of physical evidence all over Europe that there is no halachic necessity to do so.