EXETER, England, July 1 (UPI) -- External factors -- nurture -- may play a bigger part in developing personality than genes -- nature -- researchers in Britain and Germany said.
Dr. Nick Royle of the University of Exeter and colleagues at the University of Hamburg in Germany investigated how personality is transferred between generations among zebra finches.
The study, published in the journal Biology Letters, found foster parents had a greater influence on the personalities of fostered offspring than the genes inherited from birth parents.
"This is one of the first experiments to show that behavior can be non-genetically transmitted from parents to offspring," Royle said in a statement. "Our study shows that in zebra finches, personality traits can be transmitted from one generation to another through behavior not just genetics."
The researchers measured personality by placing the zebra finches in a new environment and counting the number of features they visited.
Some were shy, staying mainly in one place, while others explored widely, demonstrating a more outgoing personality. Male and female birds were then paired up and allowed to breed, the researchers said.
Each clutch of eggs was fostered by another pair just prior to hatching. Offspring personality was measured once they were adults. Offspring size was also measured and was found to be primarily genetically inherited and not significantly influenced by foster parent size, the researchers said.
Although this study considers personality inheritance in zebra finches, it raises questions about the inheritance of personality in other species, including humans.
The researchers asked: "Do adopted children inherit the personality characteristics of their birth parents or their adoptive parents? Is the environment more important than genetic inheritance in the development of personality?"