Full Idea
In the conventional standard model neutrinos have antiparticles - which spin in the opposite direction, and have the opposite lepton number.
Gist of Idea
Standard antineutrinos have opposite spin and opposite lepton number
Source
New Scientist writers (Why the Universe Exists [2017], 05)
Book Reference
New Scientist writers: 'Why the Universe Exists' [John Murray 2017], p.89
Related Idea
Idea 21169 Only neutrinos spin anticlockwise [New Sci.]