This has been going on with both hunting and show dogs for decades. Especially with breeders whose dogs have earned a "name". As a purchaser of one of their pups, it turns out that we have little to worry about. If they are deemed suitable for sale, the breeder also knows their reputation rides on that, and every other sale. They do not sell any dogs that are the least bit questionable.
The downside, however, that is very much suppressed by those engaging in this practice is pretty damn ugly. They kill a lot of puppies. A
lot of puppies. I remember when the AKC spoke very loudly against this practice, for that very reason, and it seems like it kind of died down. I'm a little disheartened to learn that some may still be doing it. It's driven by pure greed on the part of these breeders. If, as it is said, "all dogs go to heaven", I hope the scum that continues this practice of line breeding doesn't get to join them there.
Don't worry about your pups. Unless they were "fixed" before you picked them up (many such breeders insist they are, so you don't wind up breeding with someone else and taking a piece of their action), the breeder may someday request one for breeding. Most of the time they have you sign some sort of a contract that covers this, so unless you did that, you are free and clear. But don't, under any circumstances, allow this breeder to use your pups for breeding. The only reason he would want to is so that he can continue this despicable practice. Enjoy your dogs, and understand that maybe you have broken that chain, at least with them.
Oh, and congrats on the Goldens. Fantastic choice. My all-time favorite breed.
