I agree that there can be a generational gap with respect to alumni social gatherings. I would also like to add to that mix, the "type" of alumni group can effect the age factor as well. Heck, you can add single status versus those members in a relationship to the mix as well.
For the sake of discussion I'm basically talking about two "types" of alumni gatherings. One is the alumni gathering that is specific to a chapter while the second gathering is regional (city) based.
Chapter gatherings are usually more specific in nature. The events surround chapter or campus happenings such as founders day or homecoming. Events specific to the chapter's housing corporation (fundraisers) would fall under this as well. As such, alumni of the chapter - of all ages and regardless of their marital/relationship status - are more likely to attend these events simply because they have a vested interest, history and tradition with the specific chapter. And yes, alumni who didn't attend this specific campus, may "adopt" this chapter if they feel vested. So basically, all ages and relationship statuses attend.
Now since there isn't a specific chapter associated with the regional or city based alumni chapters, these gatherings tend to be more general in nature. While some events may be fraternity orientated (i.e founders day events), many events tend to be non-fraternity specific. Such as ball games, happy hours, golf outings, family picnics etc. The age of the attendees depends on the event. Those that are geared to the more recent graduate, say a happy hour, will be attended by "young" alumni while events geared to the "classic alums" -
thanks boz130 for the term - such as a family picnic are more likely to attract the "older" alum. And if the gentleman is single, he may be more inclined to go out for a night with the fraternity than the "family man" regardless if he is young or classic.
And to be clear, I am not talking in absolutes here. Members of all ages and marital/relationship status will and do attend all types of events. I just wanted to add that "other factors" can and do have an effect as to who attends.