When your child may resemble your wife's ex

Jul 27, 2016

An intriguing new study suggests children may resemble a mother’s previous sexual partner after all.

Scientists have proved that, in fruit flies at least, offspring can resemble a mother's previous mate. It is called teleogony where the offspring take on the characteristics of a mother's previous sexual partner.

The idea that the physical traits of previous sexual partners could be passed on to future children was hypothesised by Aristotle and formed part of the reason that kings were banned from marrying divorcees. But the birth of genetics dismissed ‘telegony' as a superstition which had no basis in science.

Now, however, an intriguing new study suggests children may resemble a mother's previous sexual partner after all. Scientists at the University of New South Wales discovered that, for fruit flies at least, the size of the young was determined by the size of the first male the mother mated with, rather than the second male that sired the offspring.

The researchers propose that the effect is due to molecules in the semen of the first mate being absorbed by the female's immature eggs where they influence future offspring. According to lead author Dr Angela Crean, features that run in families are not just influenced by the genes that are passed down from parents to their children but also various non-genetic inheritance mechanisms that make it possible for environmental factors to influence characteristics of a child.

To study whether telegony was possible, the team produced large and small male flies by feeding them diets as larvae that were high or low in nutrients. They then mated the immature females with either a large or a small male. Once the females had matured, they were mated again with either a big or a small male, and their offspring were studied.

Those who had originally mated with a larger male continued to produce larger offspring even when mated with a small male.

Although Dr Stuart Wigby of the Department of Zoology at Oxford University agreed that telegony is theoretically possible for any internally fertilising animal, he contended that there hasn't been much evidence for it. It is too early to say whether the same effect could occur in humans, he said.

"I'm aware that molecules in the seminal fluid of the first mate can be absorbed by the female's immature eggs, but the experiment on flies may not apply to mammals because of differences in reproductive physiology compared to insects.

The study is published in the journal Ecology Letters.

 

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