Covariances among relatives

Well, if we can do this sort of calculation for half-sibs, you can probably guess that it's also possible to do it for other relatives. I won't go through all of the calculations, but the results are summarized in Table 4

Table 4: Genetic covariances among relatives.

MZ twins ( $\mbox{Cov}_{MZ}$)	$V_a + V_d$
Parent-offspring ( $\mbox{Cov}_{PO}$)$^1$	$\left(\frac{1}{2}\right)V_a$
Full sibs ( $\mbox{Cov}_{FS}$)	$\left(\frac{1}{2}\right)V_a + \left(\frac{1}{4}\right)V_d$
Half sibs ( $\mbox{Cov}_{HS}$)	$\left(\frac{1}{4}\right)V_a$
$^1$One parent or mid-parent.