It's interesting to me that they chose to limit the polygenic risk score to the SNPs at the top 292 loci, rather than using all available SNPs, which has become more common. I would guess that they chose to limit their power in favor of ease of interpretation, but it would be interesting to understand why they actually made their choice.

It's also a bit surprising that being a morning person was associated with earlier age at last childbirth in women. I would have expected being a morning person to correlate with education attainment (which I don't believe they discussed) and therefore with later age at last childbirth (since education generally delays the age at which people start having children).