Killing of pups is common in mongoose social groups, and researchers believe offspring may do best if they hide which adults they are related to.
Concealing identity reduces the risk of attack by less-related adults, they say.
But it means mothers may not be able to tell pups apart, and therefore cannot pay special attention to their own young.
“In most species we would expect mothers to target care at their own offspring, but mongooses seem unable to do this,” said Dr Emma Vitikainen, of the University of Exeter.
“We think this is because mothers synchronise birth to the same day, and pups may have evolved to conceal their identity.
“In the banded mongoose infanticide is common, and it might be too dangerous for the pups to advertise which adults they are most closely related to, as this could expose them to spiteful behaviour by less-related group members.”
A system of adult “helpers” operates in mongoose groups, with adults often looking after pups that are not their own.
They do not choose which young to care for based on relatedness.
Dr Vitikainen added: “Intriguingly, we also found that female helpers tend to pair up with female pups, and male helpers with male pups.”
The study also found that females become more likely to act as helpers after they have given birth.
Professor Michael Cant, who leads the long-term study of banded mongooses in Uganda, said: “We know that, among adults, individuals can discriminate kin from non-kin when it comes to mating and evicting rivals from the group.
“But for pups that are vulnerable to infanticide, anonymity may be the best strategy for all.”
The study is published in the journal Proceedings of the Royal Society B.