The human body -whether by randomness or design, it doesn't matter- is built solely for reproduction. The entire purpose of 'love' is to be a lure for procreation. Every single thing a person does from exercising to brushing their hair to the clothes they wear is subconsciously based on attracting a mate to reproduce. We wouldn't have genitals otherwise. If reproduction didn't exist, neither would love. If gay -blam!- was natural the human body would be built for it. It isn't. The ONLY part of a human body built to have a male body part inserted into it is female genitals which leads to the reproductive system. Nothing else. This is an undeniable fact of nature.