Why say, I don t know, just don t say anything. The Sifsei answers that Rashi had a number of explanations, he wasn t sure which to put down. Again, there are many places where Rashi brings down more than one explanation. One can explain the words of Rashi in this manner. When a young man is involved in a Shidduch and is interested to know what his children will be like, he should look at the girl s brothers.
Children generally take after their mother s brothers.
The same then can be said in the reverse. If you want to know about the character of a man, look at his sister s children. Yitzchak was trying to prepare Yaakov for what he would find in Lavan s house. This article is provided as part of Shema Yisrael Torah Network Permission is granted to redistribute electronically or on paper, provided that this notice is included intact.