Seeds at customs

Hey everyone, I am new here and planning my first grow. I've got one question which might sound completly rediculous. I am planning on ordering seeds from dr. chronic. My friend told me that any seeds coming into the United States are sprayed with something that makes them not produce any THC when they are grown. That is why they can mail them here. He says that the only way you can grow weed with seeds bought off the internet is if they are the second generation. So he thinks you have to grow the seeds and let them pollinate, then use the new seeds to grow. I told him that is rediculous. There is no way that could possibly be true. How could customs spray something on all of these seeds coming into the U.S. that magically makes them "sterile" or whatever. I have never heard anything like this mentioned before. If this was true then how can all of you grow good weed with the same seeds you got out of the mail. I probably wasted all of your time asking this because I already know this can't be true but please respond and back me up here. Thanks