Researchers have found that the subtle tug-of-war between maternal and paternal genes is likely to track into childhood, and possibly as late as the onset of puberty.
Human development is set by ongoing interplay of parent and offspring genes.
Previous research has offered evidence of a genetic struggle for supremacy only during foetal development.
In the womb, some genes of paternal origin have been shown to promote increased demands on mothers, leading to foetal overgrowth, while genes of maternal origin tend to have the opposite effect.
However, the new analysis of rare genetic disorders suggests that conflict between genes continue past childbirth.
"Compared to other primates, human babies are weaned quite early, yet take a very long time to reach full nutritional independence and sexual maturity," said author David Haig, George Putnam Professor of Organismic and Evolutionary Biology in Harvard University's Faculty of Arts and Sciences.
"Evidence from disorders of genomic imprinting suggests that maternal and paternal genes may skirmish over the pace of human development.
"This analysis suggests that human life history, and especially humans' unusual extended childhood, may reflect a compromise between what's best for mothers, fathers, and the offspring themselves," he added.
During the study, the researchers analysed the clinical case reports on patients with four rare genetic disorders.
He found evidence that children with disorders characterized by dominance of some maternal genes - Silver-Russell syndrome, Prader-Willi syndrome, and Temple syndrome - place fewer demands on their mothers' resources.
For instance, newborns with all three disorders display a weak desire to nurse, and slower childhood growth in general.
Many also show early onset of puberty, which often marks a point at which children become less dependent on their mothers' sustenance.
However, babies with Beckwith-Wiedemann syndrome, in which some maternally derived genes are suppressed and paternal genes dominate, are born heavy with particularly large tongues.
These individuals usually end up being tall, owing to their rapid growth both in the womb and as young children. They have a high frequency of childhood cancers.
"Clinical data from imprinting disorders suggest paternally-expressed genes promote, and maternally-expressed genes inhibit, childhood growth," Haig said.
The study appears in the Proceedings of the National Academy of Sciences.