In the ongoing debate of nature versus nurture, a new study released by Nature Genetics may be rocking the boat. According to a recent study, there are 12 variants of DNA that predict when you'll have a child, and approximately how large of a family you will have. The study, led by the University of Oxford in conjunction with the Universities of Groningen, The Netherlands and Uppsala, Sweden, included an analysis of over 62 studies. Within the studies, they examined 238,064 men and women for the age they were when their first child was born, and nearly 330,000 men and women for the eventual size of their families. From the study, they managed to isolate 12 genetic variants that factor into these decisions — which until now, were primarily assumed to be influenced by social and economic factors alone.
"For the first time, we now know where to find the DNA areas linked to reproductive behaviour. For example, we found that women with DNA variants for postponing parenthood also have bits of DNA code associated with later onset of menstruation and later menopause," said Lead author Professor Melinda Mills of the Department of Sociology and Nuffield College at the University of Oxford. "One day it may be possible to use this information so doctors can answer the important question: 'How late can you wait?' based on the DNA variants. It is important to put this into perspective, however, as having a child still strongly depends on many social and environmental factors that will always play a bigger role in whether or when we have babies."
It is important to note that the effect of these genetic variants are minimal — your uterus is not lying in wait for some signal from your DNA to say "It's time" and knock you up on the spot. In fact, the authors found that the 12 variants predict less than one percent of the timing involved in when men and women have their first children. That being said, the authors do not diminish the significance of the findings, pointing to the ability to use these variants in models to predict factors like whether or not women will remain childless. They also discovered 24 genes that play roles in these variants, only some of which were believed to have contributed to these factors previously. Knowledge of these 24 genes may help women with fertility issues understand their options or anticipate issues once further research has been conducted.
Of course, at the end of the day, you are the captain of your own reproductive ship. "Our genes do not determine our behaviour, but for the first time, we have identified parts of the DNA code that influence it," wrote first author Nicola Barban of the Department of Sociology and Nuffield College at the University of Oxford. "This is another small piece to understanding this very large jigsaw puzzle."
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