The Pasuk says "ויקרא יוסף את שם הבכור מנשה כי נשני אלקים את כל עמלי ואת כל בית אבי" - “And Yosef called the name of the first-born Menasheh, ‘for G‑d has made me forget all my toil, and all my father’s house.’”
It is understandable that Yosef is grateful to Hashem for allowing him to forget all his past troubles, but it’s confusing as to why Yosef includes “ואת כל בית אבי” - “his father’s house”. Yosef’s father, Yaakov, was one of the greatest men in history. Yosef grew up with Yaakov and learned valuable lessons from him. Why would he ever want to forget his father’s house?
The answer to this question can be told through the following Mashul. A visitor once entered a presumably Kosher restaurant. Unimpressed with the religiosity of the staff, he began to inquire about the Kashrut standards. The proprietor confidently pointed to a picture on the wall of a Jew with a long beard and long flowing sideburns. He said to the visitor: “You see that man up there? He was my father!” The visitor replied: “If you were hanging on the wall, and your father was behind the counter, I would not ask any questions. But since your father is hanging on the wall, and you are behind the counter, I have good reason to question the Kashrut.”
There are many whose only attachment to Judaism is through nostalgia. They remember their mother lighting candles on friday night, they recall the long beards and sideburns of their fathers, and they reminisce about their parents' Shabbos table. They proudly tell their children about it, but unfortunately, they do not practice this way of life themselves.
Living among the Egyptians, Yosef was in danger of becoming totally assimilated in the society of the upper class. Fortunately, he remained firm in his Torah observance. Therefore, it was unnecessary for him to tell his children about his parents' observance. Yosef conducted his home life in exactly the same way as Yaakov had done, and was able to “forget” his father’s house and show his family his own home as a living example.