"And Yosef said to his brothers: 'I am Yosef. Is my father still alive?'; and his brothers could not answer him, for they were startled before him." (Bereshit 45:3)
One might ask why he asked them again if his father was still alive, when he had already asked during their second arrival in Egypt, as it is written: "Is your elderly father of whom you spoke well? Is he still alive?" (43:27), and they had already answered him: "He is still alive." It is also necessary to analyse the meaning of the expression "for they were startled before him."
It can be explained according to what we find in the Midrash (Bereshit Rabbah 84:5, cited by Rashi), that Yosef’s countenance resembled that of Yaakov his father. Therefore, now that Yosef revealed himself to them and said: "I am Yosef," he added: "Is my father still alive?", meaning to say to them: "If you do not recognize me because I did not have a beard when I left and now I do, you can still recall the face of our father, who is still alive and has a beard, and you will see that my appearance is like his."
Zera Shimshon, Parashat Vayigash, end of Art. 3
