Table 2.

Full and minimum adequate (final) general linear models after stepwise deletion of non-significant terms and scaling of numeric parameters, testing for drivers of individual sex ratios. Individual, paternal, and maternal factors are considered. Individual f offspring, father f, and mother f represent the coefficient of inbreeding of the individual, the father, and mother, respectively (n = 883). Father and mother age at conception is measured in days. The following two-way interactions (father.age.conception*father.f; mother.age.conception*mother.f; individual f*gen; father.f*gen; mother.f*gen) were included and tested for significance in the full and minimum adequate models, but none had a significant effect on sex at birth (p > 0.5 in all cases). Full model: null deviance: 1.213 on 882df. Residual deviance: 1191 on 870df. AIC: 1217. Final model: residual deviance: 1198 on 878df. AIC: 1207.

	estimate	s.e.	z	p
full model term
intercept	−0.250	0.069	−3.587	<0.001
f individual	−0.1806	0.074	−2.430	0.015
f father	0.138	0.071	1.938	0.052
f mother	−0.054	0.074	−0.720	0.471
generation	−0.192	0.075	−2.546	0.011
father age at conception	−0.010	0.075	−0.139	0.889
mother age at conception	0.076	0.078	0.969	0.332
father number offspring	0.041	0.079	0.517	0.605
mother number offspring	−0.106	0.088	−1.199	0.230
final model term
intercept	−0.224	0.068	−3.284	0.001
f individual	−0.191	0.070	−2.707	0.007
f father	0.147	0.069	2.110	0.034
generation	−0.183	0.070	−2.623	0.009