There are two ways to control your reputation: haphazardly, and professionally. Haphazardly includes not doing anything, not joining the major sites, just sticking your head in the sand and pretending they do not affect your life and business.
Do you realize that if someone with the same name as you or in a business with a similar name gains a bad reputation on line, and you are not there with your own positive presence, people may think it’s you? So by not participating in social media you may damage your own reputation.
The best plan is to join the most important sites, create professional profiles, and maintain at least a minimal, positive presence. Reserve your name and your business name(s) on the major sites so that when you decide to be more active, they will be available to you.