New research suggests that mammals may be more genetically similar to their parents than to their mothers, although we inherit equal amounts of genetic mutations from each parent.
The University of North Carolina (UNC) study found that the influence of mutant genes coming from the father is greater than the mutant genes from the mother.
Genetic mutations passed from parent to child typically appear in complex diseases involving thousands of genes.
The process by which information contained in genes physically manifests itself is called gene expression.
Scientists believe the discovery could open new avenues for treating common but complex diseases - such as various cancers, diabetes, heart disease, schizophrenia and obesity.
UNC researchers used specifically bred mice for greater genetic diversity
The research was published in the journal Nature Genetics.
Mutations that alter gene expression - called regulatory mutations - affect human health come from mother and father.
But, says UNC researcher Fernando Pardo-Manuel de Villena, "we now know that mammals express more genetic variation from their father. So imagine that a certain type of mutation is bad. If inherited from the mother, the gene would not express itself as it would express itself if it was inherited from the father. "
Second study, genetic material inherited from the father has more impact.
Villena states that the same "bad mutation would have different consequences for disease if it was inherited from the mother or father."
Research conducted by the UNC team surveyed a population of laboratory-derived mice, bred to have a greater genetic variety - to be comparable to human diversity - than typical laboratory mice.
Thus, scientists say the results will be most useful for human disease studies, as previous research was unaware of the origin of specific genetic expressions - not knowing whether they came from parents.
American research has examined three different varieties of mice that have crossed inbreeding, descended from a subspecies that evolved on different continents.
These mice cross-bred to create nine different types of hybrid offspring, in which each variety was used as a parent.
When mice reached adulthood, the researchers measured gene expression in four different tissue types.
They then measured how much of this gene expression was derived from the mother and father in each of the genes.