Twin and family studies have consistently indicated that EEG alpha power is one of the most heritable traits in humans at up to 96% for frontal alpha power in young adult samples (Anokhin et al., 2001; van Beijsterveldt, & van Baal, 2002; Smit et al., 2005; Zietsch et al., 2007). The SNP heritability observed here using LD score regression was only able to retrieve a relatively small proportion of variance of the often highly heritable EEG traits. This pattern of high twin/family heritability with a relatively low SNP heritability has recently been observed across a range of complex, neuropsychiatric traits (Bulik‐Sullivan et al., 2015a). This discrepancy could be caused by a relative large contribution of rare SNPs that are poorly tagged by the common SNP arrays used here. The SNP‐based genetic correlation analysis was more consistent with twin/family studies. Strong genetic correlations (>.70) were observed among the slower (delta theta) and among faster oscillations (alpha beta). Results from twin studies generally ranged from 0.50 to 0.90, although the twin‐based r G between theta and delta oscillation power is generally not
