Dark world – What are the potential side effects on a family from drinking fae blood?

Well, it depends largely on the version you are watching. The only real definition of powers I know is that of Dark Ages: Fae – so, supposedly – is for vampire antagonists, not vampire PCs.

That said, here are the references I could find on Vampire books. V5 and Dark Ages V20 do not mention fae, and I do not have the 1st, 2nd or 3rd edition to check them.

Dark Age: Vampire

Blockquote Rumor attributes wonderful properties to the blood of werewolves, fairies and other creatures. Experience shows that vampires who try to feed on such targets almost always end up being drained of their blood and thus unable to report the special benefits they have achieved.
Rules of nutrition, p. 164-165.

Fairy blood has strange effects on the Cainites who drink it, temporarily (or even permanently) angry. Rules of Fae, pg. 298.

Vampire the masquerade: 20th anniversary

Some vampires (such as Malkavians, Ravnos and Tremere) hunt faeries for their blood, believing it to be far more powerful than deadly blood. Among those who claim to have tasted this sweet vitae, the experience is quite varied. Some claim that fae blood tastes little or no different from deadly blood; others speak of ecstatic joy, hallucinations or transcendent experiences. Some liken him to feeling the morning sun shining once more on his face – both in his enthusiasm and in his excruciating pain. Rules of Fae, pg. 383.

No mention of Fae on the rules of nutrition.

Dark Ages: Fae

Vampires can not feed inanimate because they do not have blood. A vampire who tries to feed on an inanimate water receives only a sip of water for her problem (woe to the vampire who feeds on an inanimate fire). The fae blood of other origins, however, generates powerful effects. All the system information provided relates to the blood of change, and the effects continue until all the fairy blood has been used. The blood of the firstborn is twice as powerful as that of the changelings, which doubles the following effects. For example, changeling Summer blood adds two dice to absorb sunlight and fire, while the first summer blood adds four – and the first blood of autumn doubles the radius of its negative effect.

Summer blood adds two dice to absorb sunlight and fire, but causes the projection of a soft, false light onto the skin, inflicting lethal damage per turn to other vampires. Spring blood causes drastic mood swings, increasing charisma by 1 point when he is in a good mood, but increasing the difficulty of resisting the +1 frenzy. Autumn blood allows a vampire to read the surface thoughts of others (as in Auspex 4), but all the thoughts of those within a ten-yard radius invade him in spirit (pass one point of will per scene to focus on specific thoughts). Winter blood increases each physical attribute by one point, but increases the need for blood, so that any blood consumed produces only half of the normal blood points. Solstice blood does not have any special effects. Vampire Systems, pg. 181.