tl;dr: put your personal off-topic content on another site.
Your off-topic content is one thing - and a minor detail for off-topic content created by your community.
If you get a community going - which is nowadays probably a goal for most sites - you will need a place where you can direct off topic content to.
Most technical forums have a "Lounge" or "General discussion" area which serves as a sink for the desire of off-topic exchange, and keeps the technical areas on topic. Usually, your pwoer users will help you "police" the technical areas - having or not having a "Lounge" area is the difference between "your jokes are not welcome here" and "not here please, join the fun at /lounge".
However, this is as much a risk as a chance: the rules you enforce (or don't enforce) there will shape the community. You do have to deal with the legal swamp of unreviewed user content being publicly visible. It still helps to keep the "dirt" in one place, though.
Anyway, I would strongly, sternly and repeatedly recommend against posting your personal off-topic content anywhere on a site you have any community administration rights.
Step 1: You as an admin, you will have to remove certain posts, e.g. in the interest of the community or for legal reasons. You will have set rules, and enforce them.
Step 2: You, as an admin, will - by error, naivety or ethanol poisoning - post content that's borderline inappropriate. No matter how you deal with this
Step 3: you will be dragged into a discussion about censorship, entitlement, and abuse of power. You will face discussions that are "you removed X, but did not remove Y".
I've seen a few power users rise into the rank of desperately needed community moderators, only to fail with a conflict between their moderaiton respnsibilities and their own content. Result: A lot of pointless shit hitting fans, disgruntled users, a lot of time wasted, disillusions.
- keep your personal content off-site. Domains are cheap, blogs are free
- if you have a community: allow (some of) your users to advertise a link to their "personal page" e.g. in their profile page. Use this to link to your personal page, where you keep your personal stuff.
- without a community, put that link somewhere where curious people find it - e.g. the "about" section
- keep all discussion about your personal content away from the site you mod.