  Dynamically linking a meteor shower with its parent body can be challenging.
This is in part due to the limits of the tools available today (such as
D-criteria) but is also due to the complex dynamics of meteoroid streams. We
choose a method to study chaos in meteoroid streams and apply it to the Geminid
meteoroid stream. We decided to draw chaos maps. Amongst the chaos indicators
we studied, we show that the orthogonal fast Lyapunov indicator is particularly
well suited to our problem. The maps are drawn for three bin sizes, ranging
from $10^{-1}$ to $10^{-4}$ m. We show the influence of mean-motion resonances
with the Earth and with Venus, which tend to trap the largest particles. The
chaos maps present three distinct regimes in eccentricity, reflecting close
encounters with the planets. We also study the effect of non-gravitational
forces. We determine a first approximation of the particle size $r_{lim}$
needed to counterbalance the resonances with the diffusion due to the
non-gravitational forces. We find that, for the Geminids, $r_{lim}$ lies in the
range $[3;8]\times 10^{-4}$ m. However, $r_{lim}$ depends on the orbital phase
space.
