Create simulate.twin.r

Simulation tools for power study of structural equation model (SEM). Generates twin based covariance matrices according to the additive ACE decomposition and the approximate 50% genetic similarity in dizygotic twins (zygosity passed as sequence of 1, 2 variables, i.e. number of zygotes). Cholesky compositions are taken for each matrix and then cross prodded with independent random normal data generating a sequence of correlated observations.