Parents who excessively worry about cleanliness could be damaging their children's immune systems, a new survey claims.
The ICM study found 60% of people believe children should be protected from all bacteria.
But they do not realise that some exposure is critical in building up the immune system.
A baby is usually exposed to bacteria in the birth canal, but a rise in Caesarean births and a drop in breastfeeding means some youngsters are starting off with under-developed systems.
This is then compounded by parents obsessing about antibacterial wipes and antibiotics, the research added.
Professor Ken Jones, an immunologist at Cardiff School of Health Sciences, said: "With the huge media attention around dangerous bacteria such as MRSA, the marketing hype pushing total annihilation of bacteria via wipes or sprays, coupled with the dangerous reliance on antibiotics for almost any infection, there is a real concern that we are misunderstanding bacteria and the vital role some bacteria can play in our overall health and wellbeing and the development of our young."
He added: "The PlayStation generation no longer play outside with plenty of other kids as they used to. We live in smaller families and in less rural locations.
"All these factors mean children are less exposed to the variety of bacteria they used to be, which is crucial to develop the immune system."
His advice is to strike a balance by encouraging children to play outside, but at the same time ensuring they wash their hands.