As far as my situation goes, I'm not sure many people really know about it! I remember when I was in an academic honor society as an undergrad, my sister saw that it had Greek letters and didn't understand that it wasn't a sorority. She would tease me with "Delta, Delta, Delta, Can I help ya, help ya, help ya?" just because that's a famous line from TV or something. (Though, after explaining a bazillion times, she finally got it!)
She and our roommate did know about my going to informal recruitment my final semester and they were a little bit perplexed....but they didn't poke fun or anything.
Now that I'm pursuing AI, I think the only person who knows is my boyfriend. Funny enough, he's British and they don't have sororities and fraternities here. So, he's a bit bemused, he keeps asking me if it's like the Masons. I think he keeps asking that just to wind me up!
There is one good friend of mine who is anti-greek.

Back in college, she would have totally flipped out if I had joined. Now, I am sorta worried about how to tell her or how she might find out. I'm not ashamed of it, not at all! It's just that people like her are hard to convince and, really, I don't need or want a screaming lecture about the degradation of women or about how individuality is not gained by paying to conform to society or something like that. Though, after all these years, I think she accepts that I am a very different person from her. She's calmed down a little bit over the years and she might actually have a rational discussion about it with me.
Outside of one pro-greek aunt (my cousin is a Sigma Chi), I have an overall feeling that my friends and family "won't get it." However, I'm sure they'll shrug their shoulders and go along with it. After all, I'm a university administrator and they'll probably just think that it fits along with what I do for a living or something.
PNAM,
.....Kelly