When you use beer coasters as bookmarks for when you are reading beer books and mags ;D
When family game night turns into family bottling night.
you’ve used hop oil as cologne 8)
You typo “yeast” for “year” over and over again.
The ability to reuse a bottle influences the beer you buy. (always looking for 22 bombers over the 6 pack)
Your wife and kids walk by and say “Still reading about beer?” . Multiple times every day.
…when you have four different freezers at your house that serve four different purposes.
Yes! And avoid twist offs and painted labels.
…or if you stop buying past-their-prime IPAs at the liquor store because you know you can brew better and fresher at home.
When you set your house thermostat based on ideal fermentation temperatures rather than human comfort 
… When making stew, you add the peas at flameout.
You play softball with the kids and every time you throw a pitch, you think of Wyeast.
…you know a “carboy” is not a NASCAR fan.
… you are delighted that a Br’un Water spreadsheet looks like actual work on your monitor when someone comes to your office to ask a question.
… your 10 year old gives correct descriptions of what’s on tap to your guests. Then takes their orders and serves the beers.
This is even more telling when they are serving the drinks to the school board during a meeting at your house. (True story : )
Paul
Doing QC on beers that recently came on tap and the music from the stereo gets louder and louder(much to SWMBO chagrin) 
… Your 4 year old is scared at the brewpub because the “fermenter is too big”.
(Also a true story)
Sounds eerily familiar.
…or better yet, you practically stop buying beer altogether because you know you can brew better (and more economically) at home.
Yes… This doesn’t get minimized quickly when company comes by the desk