Because we can very easily say that with how many children are running around, straight relationships are far from becoming rare.
Being gay is not the same as being sterile. Sorry if this seems all too obvious to state, this is a particular peeve of mine that gets thrown around too often to combat gay rights. If everyone were gay there would still be children. Gay couples have children now, they just do it through means that are different, such as having a surrogate mother.
(edited by SirMoogie.9263)