Exactly, and the way the parent didn't seem to fit into the 'culture' was by being older.
"Frathouse culture" is an euphemism for "group of mostly white young male people who exclude people who aren't like them" - because this is what fraternities literally are.
(Recall: by definition, fraternities are young, male, exclusive - and statistically, white).
Black fraternities (well, historically black) do exist, both at HBCUs and at other colleges and universities. And one thing that's particularly notable is that historically black fraternities tend to be more public-service oriented than historically white fraternities, which are more purely social clubs.
I know they exist, and my comment was tongue in cheek, not to be taken literally.
But in every joke there is a core of truth. People use language to disparage minorities or downplay the transgressions of the majority all the time.
E.g. nationalist extremist violent acts are done by "lone wolfs" or "mentally ill" people while the exact same atrocities by other groups are done by "terrorists".
"Frathouse culture" is an euphemism for "group of mostly white young male people who exclude people who aren't like them" - because this is what fraternities literally are.
(Recall: by definition, fraternities are young, male, exclusive - and statistically, white).