[R-sig-ME] MCMCglmm question

[David Duffy]

On Mon, 16 Jul 2012, Jackson King wrote:

> Hello,
>
> I am trying to fit a simple ACE genetics model with twin data, but am
> having difficulties implementing it in MCMCglmm. The data consist of both
> MZ and DZ twin pairs. The MZ twin variance can be decomposed into ACE;  the
> DZ variance can be partitioned into CE and twin/family specific variance
> and unique genetic variance. I am unable to retrieve these components after
> running a model where unit and twin level variance components are
> estimated. Any thoughts on how to do this? Do I fix the DZ genetic variance
> to be half of the MZ in the prior?

You want to put the inverse A and C matrices into ginverse (see 
?MCMCglmm), though I think C could just be coded as a household effect in 
random so that the appropriate covariance matrix will be generated for 
you.