Earlier quoted context omitted.
It wouldn't be different at all. Mostly we did use units of twelve for everything. Why do you think there are twelve inches in a foot and twelve pence in a shilling? Asking what the historical difference would be if we wrote our numbers in base 12 instead of, variously, 10, 12, or 20 (all historically common, and 60 is prominent too), is like asking what the historical difference would be if we wrote our words in Gre…
Of course it would be different. I'm well aware of historical numbering systems, and their applications. My point is that if base-12 was biologically natural, instead of more effortfully useful , there would be many differences in the way we do things -- although of course we would be mostly unaware of them, as a fish in water. There would be no metric-vs-imperial units dichotomy, for example. (EDIT: Or at least the…
No, they wouldn't. This would be a very minor effect, because the primary determinant of sizes and amounts is how big you need something to be, or how much of it you need.
Instead, you'd see the same thing we already do see: contexts in which an existing unit was difficult to work with would be given their own units of a more convenient size. Consider how horses are measured in increments of four inches, or how soft drinks are sold in unit sizes of 12 ounces, 20 ounces, and 67.6 ounces.
The units aren't called that, of course; those sizes are "one can", "one bottle", and "two liters".