While "google"-ing certain theories in order to try and not post what others already stated and thus lose my individuality , I thought to type in "theory of sex", just for the heck of it. For my effort the gods of Google search gave me this phrase on top of the list: "A third theory is that sex evolved as a form of cannibalism".... WOW !!!
I knew that symbiosis evolved as a form of cannibalism and this is the reason why today we have mitochondrial DNA as separate DNA from the nucleus but sex evolving from cannibalism?
No doubt sex ended in cannibalism for a lot of species ,but thinking that we have sex because a billion years ago some cell thought it was kinky not to digest the whole DNA molecule of another cell that is pure win.