The scientists from University of Utah School of Medicine said it is not uncommon for cells in the brain to preferentially activate one copy over the other.
For the study the researchers did an experiment on one region of the newborn mouse brain. The results showed that there are times when the children choose even the best prefer one parent over the other.
According to the scientists the finding breaks basic tenets of classic genetics and suggests new ways in which genetic mutations might cause brain disorders.
The study also revealed that about 85 percent of genes in the dorsal raphe nucleus differentially activate their maternal and paternal gene copies. These genes are known for secreting the mood-controlling chemical serotonin.
The scientists found that after ten days the landscape shifts in the juvenile brain, with both copies being activated equally for all but 10 percent of genes. Additionally, more than an oddity of the brain, the disparity also takes place at other sites in the body, including liver and muscle. It also occurs in humans, said the researchers.