There are ways to prevent anyone from looking up what you have done on social media. If you look hard enough and double check all the feeds that could be public then change them to private through the settings, then even people you have friended cannot see what is there. I used my public account which has all of my family on it and they are pretty much addicted to that site. If you are curious as to what your site looks like from another persons account then you can click [View As...] under your profile. I've confirmed that you can hide everything by not only using that but also by using my fake account. If you have any doubts then like and comment on random things and groups after fiddling with your settings and check if it shows up anywhere.