Concluding this chapter the Chofetz Chaim warns that it doesn’t make a difference whether someone else or anyone in your household is speaking lashon hara, even your parents you can’t just accept what they said if it is lashon hara.
What’s worse, the Tanna Divei Eliyahu in chapter 21 says if one hears his parents say lashon hara or any other inappropriate speech and acts as if he doesn’t hear them then there is a severe punishment that you all will not fill up your days and years, not necessarily that you’ll die before your time but you might not be able to live life to the fullest. Meaning, maybe a person will get a stroke and won’t be able to function for many years but if he would have stopped this speech in his house then he would have had all his strength and faculties even in his old age until he dies.
However, the Chofetz Chaim is very careful to emphasize that when one rebukes his parents or even anyone in his household it should be done with soft language and emphasizing the severity of the punishment for speaking lashon hara and the reward in the World to Come for not speaking.
Also, the Chofetz Chaim emphasizes that you shouldn’t yell at your parents for transgressing the Torah rather you respectfully and gently say something like “even if what you are saying is true the Torah still says it’s never right to speak lashon hara about your friend” or judge favorably the person being talked about until the speaker will stop talking the evil speech.
Practically speaking the truth is this is very hard to do however by building awareness of the issue hopefully it will deter others especially those in your household from talking lashon hara. For example, putting literature about lashon hara on your coffee table which they can pick up and read on their own if they wish. It might get them curious and eventually more careful of the issue. Also, if you can slip into a conversation about how terrible slander in the media and Politics has become in our world today, people can relate to how detrimental it is, destroying people’s lives and making everyone feel bad they might get the message that slander can be harmful even in our day-to-day life with our friends and those around us. This way making subtle impacts on our family. Another idea might be to start reading the Chofetz Chaim lesson a day at the dinner table or at least on Shabbos with the family together which raises awareness.