Genes Do Influence When You Have Your Firstborn – Ignoring Biological Clocks May Not Be A Good Idea

Women may be ignoring their biological clocks and delaying childbirth, but genes may still have some say in the matter, indicate a couple of studies that concluded recently.

There’s an interesting contradiction being observed in the modern society. It appears human females are actually evolving to become fertile younger and younger. In other words, girls are now biologically ready to bear children at a much younger age. Needless to say, this makes them more susceptible to teenage pregnancy.

However, statistics indicate women are now having babies on average four to five years later today than in 1970. The average age of first-time mothers now seems to be between 28 and 29. After analyzing the DNA of almost 7,000 women in the UK and the Netherlands, researchers discovered that around 15 percent of the variation in the age women have their first child and 10 percent of the difference in the number of children they have can be traced back to genetics, shared lead researcher Melinda Mills from Oxford University in the UK.

“What we see in this study is a clear genetic component linked to the age of mothers when they have their first child, and to the number of children they have. But this genetic component should actually be making us have children earlier and earlier and so the fact that we’re delaying the process can only be attributed to societal factors.”

In simpler terms, though genes might allow females to have children at an earlier age, they are intentionally delaying the birth of their first child. Such conflict of interest with the genetics and societal norms could play spoilsport for future generations.

To investigate exactly how genes influence fertility, 4,300 unrelated women and 2,400 females who have a twin in the UK had their DNA analyzed. Correlating the same to the age when they had their first child as well as how many children they eventually gave birth to, the researchers were able to prove there are a series of genes that influence how young a woman has a child and how many she might have.

While these studies might look like a bad omen for women who are quite reluctant to have babies early on, the findings might have a positive side. If our genes do play a definitive role in determining the ideal and most fertile period in a woman’s life, a simple DNA test might one day advise how long a modern-day woman could delay having a child as well as the most opportune time to start trying.

[Image Credit | Jamie Grill / Getty Images]