"Yitzchok loved Eisav, for game was in his mouth, but Rivka loved Yaakov (25:28)."
"One who spares his rod hates his child, but he who loves him disciplines him in his youth (Mishlei 13:24)." Yitzchok loved Eisav, and therefore Eisav became a terrible sinner because Yitzchok did not discipline him. Whoever does not discipline his son, will hate him when he goes astray. Examples include Avraham and Yishmael, and David and both Avshalom and Adoniya: "All his [Adoniya's] days his father had never saddened him [by] saying 'why have you done this?' (Melachim I 1:6)."
"One who loves him disciplines him - this is Avraham who chastised Yitzchok and taught him Torah and guided him in his ways. This is Yaakov, whose father Yitzchok taught him Torah and disciplined him in the Yeshiva. Yaakov chastised his sons and punished them, and taught them his ways. Ultimately a son who is disciplined loves and honors his father."
-Tanchuma Shemos 1
The Torah does not hide the errors of our great men -they are thereby made greater and more instructive (Rav Hirsch 12:10). As long as Yaakov and Eisav were little, both had exactly the same teaching. This was a mistake. The great law of education, bring up each child in accordance with his own way (Mishlei 22:6), was forgotten. Had Yitzchok and Rivka trained Eisav differently, according to his nature, early enough, he could have helped Yaakov (ibid 25:27).
Yitzchok loved Eisav, who served him well, but he ultimately hated Eisav. Rivka loved Yaakov (present tense), based on his wonderful nature which engendered even greater love (Netziv 25:28).
Raising children sometimes demands selflessness. Yitzchok allowed Eisav's service to interfere with disciplinary action. Yitzchok's eyesight failed because Eisav bribed him, and bribery blinds (Shemos 23:8) (Da'as Zekeinim MiBa'alei HaTosafos 27:1).
Earlier, Eisav was disciplined too much, raised in the same way as Yaakov. Sometimes "one size fits all" education is simply more expedient. Moreover, a tightly disciplined child is a source of pride to a parent. However, a child who needs more "space" in early youth must be reasonably accommodated. This requires a careful analysis of the child's nature, and a great deal of patience and flexibility.
One who is born during the hour of Mars (maadim - red) will be a man who spills blood: a bloodletter, a shochet, a mohel, or a [murderous] thief (Shabbos 156a). A parent who attempts to raise such a child as a rosh yeshiva instead of a doctor, shochet or mohel, may cause him to become a murderer. Instead, the child must be raised according to his way, utilizing his particular nature to serve Hashem (Gra, Mishlei 22:6).
Eisav was the ultimate red one [adomi, 25:25]. The sword by which he lived (27:40) could have been sublimated to help Yaakov, rather than to kill him.
Extremes of harsh discipline and undue permissiveness must be avoided. According to Rav Shlomo Wolbe zt"l, "the rod" need not refer to physical punishment, or even verbal rebuke. The rod of pleasantness (Sanhedrin 24a), of encouragement, of positive reinforcement, is preferred (Planting and Building, p. 35).
Certainly, an angry parent who loses control and strikes or scolds his child, damages his child. In our times, such measures may be inappropriate even when the parent controls himself. They may lead to low self-esteem and/or rebellion (ibid pp. 36-38, based on Rav Chaim of Volozhin).
Yet a parent dare not ignore the bad behavior of his child. A father who hears his son say silly things and responds "he is a child, let him play" causes terrible harm to the entire family (Bamidbar Rabba 4).
Too many American parents have abdicated their disciplinary responsibility, leading to disastrous results. The Torah world has been affected by this excessive permissiveness as well.
Children must be taught that certain behaviors that are acceptable in American society are prohibited by Torah law. Of course, parents must teach primarily by example. If a parent says, or does, "silly things", he can hardly expect his child to refrain from such sinful words or deeds.
Indeed, raising each child according to his way is an arduous challenge. It requires careful analysis of what "his way" is. It demands delicate balance and extraordinary patience to implement the individualized chinuch method appropriate for "his way".
Finally, tefillah is critical. The tears shed over the centuries by fathers in shul and mothers during candle-lighting work wonders in Heaven. In addition, a child who discerns that his parents are crying as well we trying their best to raise him properly is more likely to honor them by fulfilling their fondest wish.