If My Grandmother And Your Grandmother Were Sisters What Does That Make Us?

It makes you second cousins. The offspring of full  sisters are first cousins, sharing,on average 1/8 of like genes. The offspring of first cousins are therefore second cousins sharing,on average, 1/32 of like genes.   Second cousins share a set of great grandparents in common. In this case the set are .the parents of the two sisters.

Second cousins. No, that's not cool....