There is a great deal of difference in coming out with something like a statement such "my favourite colour is blue" which is your opinion and no one could argue with and suggesting you know all about the biology and psychology of this subject.
What Bathsheba said was "Everyone is entitled to have an opinion about anything they wish without thinking it's their business" They are - in their heads but if you start spouting off as if you know the facts you must expect to be challenged. You are going from chat to discussion/debate. Between the two of us only you think I am trying to create an argument. I think I am just presenting facts, which I appreciate you may not like but that is really your issue, not mine.