Table 2.

DNA methylation variation decomposed into genetic and environmental components

Source	Mean PV	Maximum PV	First quartile PV	Third quartile PV	Nominal Sig. sites	Genome-wide Sig. sites
G	9.5%	99.20%	0.67%	12.98%	162,800	24,101
K	7.2%	97.10%	0.00%	11.05%	59,117	1531
F	1.2%	19.10%	0.00%	1.84%	1946	0
S	1.4%	46.30%	0.00%	2.24%	23,600	78
C	2.1%	33.50%	0.00%	3.18%	14,514	0

Proportion of variation in methylation levels at the 639,238 studied CpG sites explained (PV) by G (common SNP-associated additive genetic component), K (pedigree-associated additive genetic component), F (shared environmental effects between nuclear family members), S (non-additive genetic or shared environmental effects between full siblings) and C (shared environmental effects between members of a couple). The number of CpG sites that were significant in the component of interest, both at nominal and genome-wide level (Sig. sites at nominal and genome-wide levels) is also shown for each of the five components fitted