I see that my computer seems to display U+2019 (RIGHT SINGLE QUOTATION MARK ’) with a glyph identical to U+02bc (MODIFIER LETTER APOSTROPHE ʼ). WordPress and most other software seem to convert U+0027 (APOSTROPHE ') to U+2019. That's odd, because nine out of ten times, it's an apostrophe, not a single quote.
Of course the crotchety of fASCIIst in me says stick to the 0x27. Straight apostrophes were good enough for every great novel ever make on a typewriter.