“Cancer is just a rogue cell doing it’s own thing.”
True, except for that invasive little apostrophe.
One of the most confusing aspects of the English language is its (see that? its, not it’s) no-apostrophe possessives.
If something belongs to Simon & Garfunkel, it’s Simon & Garfunkel’s, not Simon & Garfunkels — but if it belongs to them, it’s theirs, not their’s. Possessive, but no apostrophe.
That boy is hers, not yours — right? You don’t write “her’s, not your’s.”
No apostrophe for whose, either. Nor for ours. Certainly not for his. (That would be silly: “We welcome Hi’s Majesty the King”? Uh, no.)
And the only time you use the apostrophe in it’s is when you mean to say it is or it has. (“It’s been a hard day’s night….”)
Why this aberration in our dear English language? Here’s my theory: It happens with pronouns — and PRONOUNS ARE LAME.
Convince me otherwise.
English Is A Complicated Language 