  We determine the strangeness and light quark fractions of the nucleon mass by
computing the quark line connected and disconnected contributions to the matrix
elements m_q <N|qbar q|N> in lattice QCD, using the non-perturbatively improved
Sheikholeslami-Wohlert Wilson Fermionic action. We simulate n_F=2 mass
degenerate sea quarks with a pion mass of about 285 MeV and a lattice spacing a
approx 0.073 fm. The renormalization of the matrix elements involves mixing
between contributions from different quark flavours. The pion-nucleon
sigma-term is extrapolated to physical quark masses exploiting the sea quark
mass dependence of the nucleon mass. We obtain the renormalized values
\sigma_{\pi N} = 38(12) MeV at the physical point and f_{T_s}=\sigma_s/m_N=
0.012(14)^{+10}_{-3} for the strangeness contribution at our larger than
physical sea quark mass.
