Which of the following sentences is correct?
He's a friend of my family.
He's a friend of my family's.
Which of the following sentences is correct?
He's a friend of my family.
He's a friend of my family's.
To my surprise, both have been used by authors (after checking on NGram). In fact, there is another variation as well - my family friend.
Personally, I may prefer the first one because the preposition 'of' already takes care of the possession. And thus, the apostrophe there looks redundant.
I suggest none of those is as common as “… a friend of the family…”; prolly not even put together.
One might prefer the first but never because the preposition “already takes care of the possession” or makes the apostrophe look redundant; that simply can’t be.
– Robbie Goodwin Jul 09 '18 at 20:38