While you are certainly not the first parent to ask this question, fortunately the resounding answer is “No!”  All the research indicates that the opposite is true.  Not only are children whose parents talk to them about healthy sexuality less likely to be promiscuous, there are a number of other wonderful effects.  Let’s talk about why.  Whether or not children let on, your opinion as a parent is invaluable.  Your values and connection with them is a commodity they crave.  They instinctively look to you for truth and guidance.  And if you can impart those values in a calm and non-judgmental way, they will absorb it.
One analogy I like to use with parents is to tell them to imagine that they live in an inner-city rife with drug dealers.  Imagine you can see them out your window.  Now imagine sending your children out the door every day for school and never talking to them about drugs.  Sending them out the door hoping and praying they never become addicted to drugs.  The scenario is unthinkable.  None of us would ever do that.  Apply this scenario to pornography, which not only lurks outside our homes, but often enters our homes, despite our best efforts, through the TV, internet, and other devices.  It is equally unthinkable a situation to simply hope and pray our children will not be influenced by the unhealthy sexual messages they see around them.