Appendix 1—table 2. Estimated marginal means and standard errors across relatedness and sex categories.

	Relatedness				Sex Category
	Full siblings	Maternal half	Paternal half	Non-siblings	Female-female	Male-male	Mixed-sex
Play	2.35 (0.40)	1.72 (0.33)	0.99 (0.09)	1.33 (0.10)	1.16 (0.16)	2.23 (0.26)	1.36 (0.15)
Grooming	1.94 (0.43)	1.44 (0.27)	0.22 (0.03)	0.27 (0.03)	1.57 (0.19)	0.30 (0.05)	0.56 (0.07)
Proximity	42.5 (3.6)	41.4 (2.9)	14.2 (0.7)	15.5 (0.6)	30.4 (1.7)	22.8 (1.4)	22.4 (1.2)
Aggression	0.41 (0.07)	0.44 (0.08)	0.55 (0.03)	0.59 (0.03)	0.39 (0.05)	0.62 (0.06)	0.48 (0.04)