How do you handle it?

[Egapal]

What if they don't ask, but offer info such as keeping two balls together and talking in a sense that they know what they are doing?

In that case I would say "I would never keep two balls together for longer than necessary to breed should I decide to to that some day." If they then try to tell me how they have done it for years. I usually say something like "People kept other people as slaves for years and as it turns out it was wrong the whole time." If they start going into specific reasons why its ok then I will go into specific reasons why I don't think it is ok.

At the end of the day I tend to give advice when I feel its needed at the first sign that I can get away with it. I give advice with reasons and site a reference. There are two basic ways this can go. Either they take the advice and continue to talk about the topic, which is fine. Or they stop talking to me altogether or at least about the topic. That's usually fine too. I have to much going on to surround myself with people who are proud of how wrong they are.