I have not one but many secret lives, some present, some in the past..
the price you pay is harsh because you have to keep things compartmentalized
and now with technology and social web, things are overlapping more and more
which creates its own set of challenges.
its nothing like supporting extremists, or drugs or strippers, or affairs.
having multiple lives and maintaining them is possible if you
all i can say is if I fill a room with different people from different time periods, different groups and different places, and they talk about me, they will feel they are talking about a different person.
it is a lonely existence in many ways because a 100% of who you are is only known to you, I mean that is the case with all, but others may know 90% or 80% of who you are. I have to admit, that no one is even remotely close to that number..
sometimes you keep aspects of your life hidden from others because you dont want to hurt them. lets say secret societies for instance, if one is a member while the parents have strong reservations about it, well, maybe its best that they not know.
Or maybe due to your skillsets, cultutal and language understanding you have been tapped to do off and on work and family is not in agreement because they think its dangerous, but you feel strongly about it, why tell them?
or that one special summer with a special someone, where both of you knew it was only a summer thing on the sun drenched shores of the mediterranean, you were young, you had a great time, it would always be a cherished memory, but cant be shared with anyone for cultural religious or emotional reasons then or now.
or while you were a model student leader running student govt and campus leadership events, you were doing ecstacy at raves during the weekends 2 states away just to maintain a distance..you know
okay all of the above was just BS 
gotcha…
or did I…