Consistency

I've never brewed the same recipe twice before. I wonder how close it would be to the first time if I did.

I wonder how many variables actually affect the beer substantially enough to perceive a difference.

Lets assume you have the following variables consistent:
sanitation
viable pitching yeast amount
Same exact ingredients in the same exact amounts
same exact equipment.

Do you think it would be possible to make a beer that wouldn't be almost identical? I don't mean by purposefully trying to make it different, I mean just by happenstance.

The biggest one is the constant fermentation temps as that will be a big variable which will affect it the most.

yeah good point. Even a few degrees difference can make a massive difference with some yeasts.

Mashing Temps, brewing temps, water source. Even the biggest breweries blend batches to have a consistent end product. Consistency is maybe the biggest challenge in brewing.

Wow, those all certainly could all impact flavor. I wonder if bigger breweries aren't more effected by things like yeast mutation and hop quality rather than process though.

For us small home brewers, I think process has a lot to contribute as well. Ambient temperatures, consistency of grain crush, timing of additions, rate of draining wort, flow rate if fly sparging or dwell time if batch sparging all contribute some changes (and I'm sure there are other process variables that I didn't list) which can add up in the end. I've repeated several recipes as exactly as I could and getting fairly good repetition in measured results. For the most part, I can pick out slight differences batch to batch. Some may be due to process, or the other variables you listed and some may be due to age of the beers when compared.

Wow good points. It's tough to quantify variables as being flavor-forming without any comparisons.

I noticed formations on my fermenting wort this time because of vorlauf time was considerably decreased.

Also my boil was inconsistent. I turned the burner down because I didn't like the noise it made and immediately noticed the surface lost its roll. Though probably still 212*F I wonder how much rolling effects coagulation and hop extraction as well as the reduced heat reducing Maillard Reactions.

Also I randomly switched to a 90 minute boil vs. 60 minute because I was using Pilsner malt Even though I've never had problems with DMS. But yet another inconsistency...

My Immersion chiller also kills my boil for like 10-15 minutes when I drop it in. This is with the reduced heat setting, but certainly effects my late hop additions.

I wonder if anyone on HBT brews exact clones of their own beers?

I noticed that my results become much more consistent when I switched to a 90-minute boil with first hop addition at 60 minutes. It made a big difference in nailing down my volumes, OG and bitterness consistently versus trying to add the hops just when the boil started.