They discovered that although the second male fly technically fathered the offspring, the little ones’ size was determined by what their mother’s first sexual partner ate when it was a larva. So if the fly had eaten a high-nutrient diet as a larva, it would go on to produce large offspring. The researchers hypothesized that this is due to molecules in the first mate’s semen, which are then absorbed by some of the female’s immature eggs. Those molecules determine the traits of offspring when the female’s eggs are inseminated by other males later on.
Aristotle’s concept of telegony predicted this long ago: His theory postulates that males leave a mark on their mate’s body that influences the offspring’s traits—even if the child’s father is actually someone else. This theory was dismissed in the early 20th century, however, because it conflicted with pioneering genetics studies.
But this discovery doesn’t necessarily contradict Gregor Mendel’s theories of genetic variation; rather, it means there is more to discover about how traits are inherited. Researchers still don’t know why size is a trait passed on by a first mate, as opposed to other traits, for instance. It’s also unclear if this variation rings true for other species. Don’t worry, though: Crean says it’s doubtful that it exists in humans.
Article Appeared @http://www.newsweek.com/can-former-sex-partners-influence-offsprings-traits-274874