  We examine the effects of dynamical evolution in clusters on planetary
systems or protoplanetary disks orbiting the components of binary stars. In
particular, we look for evidence that the companions of host stars of planetary
systems or disks could have their inclination angles raised from zero to
between the threshold angles (39.23 degrees and 140.77 degrees) that can induce
the Kozai mechanism. We find that up to 20 per cent of binary systems have
their inclination angles increased to within the threshold range. Given that
half of all extrasolar planets could be in binary systems, we suggest that up
to 10 per cent of extrasolar planets could be affected by this mechanism.
