I don’t believe it’s as codified in the US as this thread might lead one to believe.
Good to know, I was starting to worry. 
1/4 Irish descent.
Didn’t think about it in the sleepy morning after getting up at 4:45 a.m.
Wore purple and periwinkle blue.
I voted “deliberately wore green and I’m of Irish descent” because that is technically true, although I could have gone with several of the other options. First, I have a lot of green clothes and my coat has green trim, so I’m likely to be wearing green on any random day in March. And up until just a couple of years ago I’d have said I wasn’t of Irish descent; through genealogy research I’ve found I’m at least 1/16 Irish, but this was news to me. I didn’t grow up with any sort of Irish-American family traditions. FWIW I suspect my Irish ancestors were probably Scotch-Irish Protestants, and thus probably wouldn’t have been into the whole “wearing of the green” thing anyway.
No Irish ancestors and I guess I’d say “other”? I may or may not wear green on St. Patrick’s day but it has absolutely no relation to it being St. Patrick’s day. It’d be related to if what I wanted to wear* happened to be green.
I can’t say I’m apathetic, though. I won’t go out of my way to NOT wear green, but I’ll get really irritated at any comments about my wearing/not wearing of it. I guess basically I care about people thinking I should care one way or another. 
- which may be influenced by: my mood, the weather, if I’m low on clean laundry, if I happen to notice a shirt that I had sorta forgotten about and haven’t worn in awhile, etc.
If I wear green, it’s to do with Esperanto, not Ireland. Or it’s random. I don’t have a lot of green clothes, and even fewer orange ones. I did text an Irish woman I know to wish her her Happy St Patricks Day though. 
Some Irish ancestry here. Wore a green shirt - I always wear something green on 17/3 - plus my leprechaun earrings. And my elder son’s name is Patrick.
I’m not Catholic and to the best of my knowledge I don’t have any Irish heritage (although it wouldn’t surprise me if it turned out that I did), and St. Patrick’s Day just doesn’t register on my radar at all. Even if I’d remembered (or, more likely, someone reminded me) that March 17th was St. Patrick’s Day, it wouldn’t have elicited anything beyond “Really? That’s nice”. Nothing against it, but no particular reason to observe it, either.
I slept most of the day, so I was wearing grey (my pyjamas)… Not Irish (Scots/English, with a bit of French.)
I wore green. Irish upbringing. Blah blah blah.
The biggest problem with St. Paddy’s Day is the aftermath of all the corned beef and cabbage. Especially the cabbage.
I work in retail and the cabbage farts the past two days in our store were plentiful. One lady, not 3 feet from me, let a huge wet raspberry rip and then just stood there like she didn’t do it. That sucker lingered like mustard gas. THEN she gave me a look like I did it.
When I remember, I wear green. Usually I don’t remember. It is then possible that my boxers are green, since some of them are.
Like my Irish grandfather, rest his soul, I wear black on St. Patrick’s Day.