In the beginning of Parshat Toldot, the Torah makes a point of telling us that Avraham fathered Yitzchak. In contrast, when Yishmael was born, it says that he was Avraham’s son, but mothered by Hagar.
The Keli Yakar explains that we are being told which parent had the greatest influence on their son. Avraham was the dominant figure in Yitzchak’s life, and Hagar was the major influence of Yishmael.
This also explains why Yitzchak grew up to be a great Tzaddik, and Yishmael was a “wild man.” Both Hagar and Yishmael ultimately did Teshuva, but one’s character is formed during one’s youth.
Sara Imeinu was given credit with having the foresight to realize that she must keep her innocent and pure son, Yitzchak, far away from Yishmael’s negative influence. Avraham was not happy about this, but was told by G-d, to listen to his wife.
Parents need to understand the enormous influence they have on their children. The children watch their parents very closely. They see the flaws of their parents, as well as their strong points.
Parents should try to be deserving role models. They guide their children with their actions, much more than by their words. Children are smart and they see everything.
Rav Meir Kahane once spoke about this very subject. He was talking about young boys coming home from Hebrew school, all excited about telling their parents about Kashrut laws. They were hoping they would now have a kosher home.
The parents were ready for such a possibility, and they disappointed their children by telling them, “We didn’t send you to Hebrew school for that!” Rav Kahane’s comment was, “You can never fool a child, who will walk away thinking that he has phony parents.”
We must attempt to follow the example of parenting of Avraham, so that your child will grow up like Yitzchak. You certainly don’t want to be like Hagar, and end up with someone like Yishmael.