Here is how sex evolved.
This part of the post is where I explain the process. While I'm doing that, you make up some reason to protest my information, or ignore it, whichever is more convenient. As I go into different levels of detail and explain the various advantages organisms that mated had over organisms that didn't and use terms like mitosis and fertilization and pollination, you rack your brain for that word you always use, what was it, oh yea, video, remember to ask for a video, and as I sum up my points with a few links and some quotes, you hold your bible up to the screen again and claim god did it and fend me off one more time.
I hope my explanation was useful in your quest for reliable information and the truth.