Table 1.

Expected covariances for X-linked traits^a

Relationship type	Generalb,c	Dosage compensation
Male-male	P1σ2Xm	2P1σ2Xf
Female-female	2φσ2Xf	2φσ2Xf
Male-female	(1/√2)P1σXmσXf	P1σ2Xf

^aExpected additive genetic covariances due to the X chromosome without and with assumption of dosage compensation [4].

^bP₁ and P₂, the respective probabilities that one and two alleles are shared IBD.

^cφ, the autosomal (i.e., diploid) kinship coefficient = P₁/4 + P₂/2.