In our study recently published in PLOS ONE as part of the Sociogenome project funded by the European Research Council, we exploited the latest advances in molecular and quantitative genetics by applying the genomic-relationship-matrix based restricted maximum likelihood (GREML) method. It allowed us to quantify for the first time the extent to which common genetic variants influence the age at first birth and total number of children women have. Simply put, the new GREML method calculates the genetic similarity between unrelated individuals based on their genetic material (i.e., their SNPs). This genetic similarity matrix is then related to an outcome across all individuals, which in our case is age at first birth and number of children ever born. For example, if you share what we call your ‘segregating genetic material’ (i.e., what makes you genetically you) at a level of 0.05% with one group and 2.5% with another, we would say that you have a higher similarity in your fertility behaviour with the second group. Since we are looking at genetic similarity, we are then able to draw the conclusion that genes explain the variation in fertility.
‘Human Fertility, molecular genetics, and natural selection in modern societies’ by Felix C. Tropf, Gert Stulp, Nicola Barban, Peter M. Visscher , Jian Yang, Harold Snieder and Melinda C. Mills has been published in the journal, PLOS ONE, on 3 June 2015.
Media coverage included:
Women starting families later despite genetic drive – study
The Guardian, 04/06/2015, p.13, Ian Sample
Feminism overrides early-birth gene
The Times, 04/06/2015, p.23, Oliver Moody
Mother’s genes play key role in decision to start a family
The Independent, 04/06/2015, p.8, Steve Connor
Feeling broody? It’s could all be down to the genes
i (The paper for today), 04/06/2015, p.11, Steve Connor
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