Someone needs to tell Kourtney Kardashian about the 'blood is thicker than water' 

expression, after she failed to recognise Kendall Jenner in a new magazine campaign. This is kind of funny.

25-year-old The Kardashians model Kendall took to Instagram yesterday [6th September] 

to share a series of photos from a new W magazine spread for

their 50th anniversary issue. Tagging photographer

Rafael Pavarotti, in the first photo she wears a head to toe red leather 

look with matching fishnet stockings, while in a third she wears an Adidas x Gucci maxi dress.

But it was the second post - the cover - that got sister Kourtney's attention, which shows 

Kendall in a blonde Marilyn Monroe-esque wig, a floor length fur coat and a sequin dress.