How can we distinguish what is biologically determined from what people merely try to justify through biological myths? A good rule of thumb is ‘Biology enables, Culture forbids.’ Biology is willing to tolerate a very wide spectrum of possibilities. It’s culture that obliges people to realize some possibilities while forbidding others. Biology enables women to have children – some cultures oblige women to realize this possibility. Biology enables men to enjoy sex with one another – some cultures forbid them to realize this possibility. Culture tends to argue that it forbids only that which is unnatural. But from a biological perspective, nothing is unnatural. Whatever is possible is by definition also natural. A truly unnatural behavior, one that goes against the laws of nature, simply cannot exist.