I'm aware of six quarks (up, down, charm, strange, top and bottom) and their antiquark counterparts, and all are spin-1/2. That has little to do with electrons, though, since electrons are leptons, and quarks compose hadrons (protons, antiprotons, neutrons, antineutrons and mesons).
The "it's a fiddle" remark is completely correct. There is nothing magical about the ±1/2 value of spin, since it isn't an accident. If you express the angular momentum in SI units rather than as a number derived from the Planck constant (ħ), it doesn't come out to a nice round number. The fact that the value is constrained to multiples of 1/2 (all known Fermions are spin-1/2; all known bosons are integer-spin) seems to be a fundamental property of whatever the heck matter is -- and, honestly, we really have no idea what that is, which is why silly ideas like string theory keep popping up. They don't actually answer any questions. (Vibrating what? All you've done is pushed the question of "what is matter" further down the stack.) But they make the math work, and that's okay. I guess.