As a precursor to the famous hands of Esav, voice of Ya'akov scene in which the younger brother fools his father into giving him the first-born's blessing, the Torah informs us that Yitzchak loved Esav, because he had a taste for game, but Rivkah loved Ya'akov. (B'resheet 25:28). Besides the omission of a reason for Rivkah's love, the reason provided for Yitzchak's seems a bit trivial. These relationships are critical and worthy of our consideration - inasmuch as they lead to the cataclysmic blessing scene which sets the stage for the never ending struggle between the children of Ya'akov and the progeny of Esav. I'd like to suggest several approaches to explain the cause - or causes - of these loves which divided this family; father's love for the eldest, Esav, on the one hand - and mother's love for the younger, Ya'akov, on the other.
The first explanation which presents itself from the text takes us back a few verses. If we take the parents' love for the eldest as a given, Yitzchak's relationship is understood and we need to explain Rivkah's. In verse 22, we read of Rivkah's consternation at the tussling going on in her womb - and we are told that she set out to seek Hashem (more on this later). God's answer to her was that she bore two (future) nations in her womb - and that the older would serve the younger. Based on this information, we understand why Rivkah preferred Ya'akov. The natural preference for the older son is based on his future position in the family - but, since she knew that that position would be occupied by Ya'akov, she favored him.
This approach, suggested by Rashbam, hinges on two premises, each of which is debatable. The first, which is textual, is more easily overcome - the text does not "attach" Rivkah's love for Ya'akov with her prophecy. The prophecy is mentioned, then we are told of the birth of the twins and their growing up - and then of the parents variegated affections. The text does not remind us of her prophecy as a way of explaining her love for Ya'akov.
The second problem is a bit trickier - we have to assume that Rivkah never told her husband of this prophecy. Even ignoring his spiritual greatness, it is hard to understand why she would keep the prophetic message about their sons' future from her husband.
ATTRACTION OF OPPOSITES
I would like to suggest an alternate explanation - which is based on the psychological maxim of attraction of opposites. In every relationship, we seek to fill that which is lacking in ourselves - hence, those who see themselves as less than generous of spirit are attracted to the beneficent; those who are gregarious are drawn to the quiet, etc.
Rivkah grew up in a home filled with deception. The text (B'resheet 24:30) tells us that Lavan invited Avraham's servant into his house - only after seeing the jewelry on his sister's (Rivkah's) hands. Lavan's duplicity and fraudulent behavior is so much a part of his character that years later, Ya'akov ends up complaining that Lavan, as his father-in-law, had changed the terms of their agreement 10 times (31:41). On the other hand, Yitzchak grew up in the righteous home of Avraham and Sarah - who, even when needing to "bend the truth" to save their lives, did so begrudgingly (see 20:11-12).
Just before reading of the parents' divided affections, the Torah tells us that Ya'akov was an Ish Tam - literally, a "straight" person, honest and unconniving. (It is only later, when Rivkah shares some of her ability to deceive, that Ya'akov is able to trick his father). On the other hand, Esav is a Yode'a' Tzayid - lit. a "skillful hunter". Rashi, however, quotes a Midrash (B'resheet Rabbah 63:10) which expands the meaning that Esav was able to "trap" others with his words - i.e. he was a successful deceiver.
Understanding where each of the parents came from helps explain their affections. Yitzchak, who was brought up in a home of perfect honesty, was drawn to Esav's ability to "play with the truth." This ability, as we see later with Ya'akov, is not necessarily bad - if it is used appropriately. For instance, our Rabbis (Yevamot 65b) tell us that it is not only permissible to "bend the truth" in order to maintain peace in the household - it may even be laudatory behavior. On the other hand, Rivkah, who was raised in the Lavanian environment of deception, was surely attracted to Ya'akov's honesty and purity.
ATTRACTION OF THE SIMILAR
Although we accept the notion of attraction of opposites when it comes to behavioral traits and psychological makeup, the inverse is true regarding vocations, avocations and social settings. We are attracted to people who share our interests, work in the same professions, share a social circle or have a common intellectual or artistic interest.
Ya'akov is described (in the verse immediately before ours) as a Yoshev Ohalim - a "dweller in tents." Although Midrashically we associate these tents with Torah study, many commentators (Ibn Ezra, Rashbam, S'forno and Hizkuni) maintain that the simple meaning (P'shat) of this phrase refers to tents of shepherds. In other words, Ya'akov was a shepherd. Esav, on the other hand, besides being a skillful trapper, is called an Ish Sadeh - a farmer. (Parenthetically, this evokes in our memories the story of the first brothers in Tanakh - Kayyin and Hevel - and foreshadows the enmity between Ya'akov and Esav.)
Yitzchak, alone among the Avot, was a farmer (B'resheet 26:12). He was, therefore, a man of the field - the exact description given to Esav (25:27). Rivkah, on the other hand, came from a family of shepherds (see B'resheet 29:9). It is understandable why Rivkah, from a shepherding family, would favor Ya'akov, a shepherd - and why Yitzchak, the farmer, would favor Esav, his Ish Sadeh son.
KINSHIP IN WORSHIP
I would like to suggest one final resolution - which underscores the different types of spiritual experiences by which individuals are affected.
When Rivkah was upset about her pregnancy, we are told that she went to seek Hashem. If she merely prayed, there would be no need for her to "go" anywhere - the verb vaTelekh implies an intended destination - not just an aimless "going". (See B'resheet 28:10 and the Beit haLevi's comments there.) If she was praying, she could have done so anywhere. Where did she go? Rashbam, Rashi, Radak and Hizkuni all agree that she went to a prophet (Avraham, Shem and MalkiZedek are suggested). It stands to reason - and Radak implies - that she went to the residence or sanctuary of that prophet. If so, her mode of worship (in the only instance we find) is an "indoors" type. In other words, whereas some people find their spiritual "connection" enhanced when in the endless beauty of the natural world, others find their in the closed tents of seclusion and meditation. Following this argument, Rivkah was an ohel (tent) davener - her place of worship and communion with God was indoors. When we read of Ya'akov being a yoshev ohalim - a "dweller of tents", and we see the Midrashic approach -that he studied in the academies of Shem and Ever - we can see why Rivkah was attracted to him. They were drawn to the same type of experience - the indoor, meditative spirituality.
On the other hand, Esav is an outdoorsman - that much is explicit in the text. Whatever spiritual experiences call to Esav, they are of the outside world, in the great and awesome beauty of nature. Turn back to the end of chapter 24 - and we find Yitzchak meditating - in the field. This verse (24:63) is the source for the Rabbinic suggestion that Yitzchak established the afternoon T'fillah - Minchah (BT B'rakhot 26b). Yitzchak's spiritual "place" was in the outdoors - just as was that of his eldest son. It is not surprising that he was attracted to Esav, while Rivkah, the tent-prayer, naturally favored Ya'akov, the yoshev ohalim.