The sight of a chubby cheeked baby is usually enough to melt even the coldest of hearts.

But for those not lucky enough to be born with the cherub-like features many of us find 'cute', they may face a tougher time in their early years.

A review of the scientific literature has found that unattractive babies may suffer a distinct disadvantage compared to their cuter peers.

Ugly babies may suffer a disadvantage during the early years of their life compared to cute infants (stock image used), researchers have suggested. One study showed that adults were more willing to give a toy to a cute child than one who they considered to be less cute

CHILDREN WITH OLDER FATHERS ARE MORE LIKELY TO BE UGLY Older fathers have uglier children, researchers have claimed after linking age to genetic mutations. With age, sperm-producing cells do not copy a man's DNA as effectively, leading to genetic mutations. A study in the journal Nature showed that women pass on a maximum of 15 mutations to their baby regardless of their age. However in men the mutation rate was found to double every 16 years. Martin Fielder, an anthropologist at Vienna University, surveyed a group of six men and six women, showing them each 4,018 photographs of 18-20-year-old men and 4,416 photographs of women of the same age. Those with older fathers were consistently rated as being less attractive. Dr Fielder said: 'The effect is very visible - someone born to a father of 22 is already 5-10 per cent more attractive than those with a 40-year-old father and the difference grows with the age gap.' Advertisement

It claims that adults are instinctively drawn to the large round eyes, oversized head, high eyebrows, chubby cheeks and dimple chin that makes infants appear cute.

This is thought to be due to the way our brains have been hardwired by evolution to find these typically infantile features attractive and so lavish our care upon them.

But studies have shown that this also leads adults to unconsciously favour youngsters with these features, to the psychological detriment of less attractive youngsters, according to Vox.

For example, when faced with a cute and less-cute baby, adults tend to prefer to give a toy to the cuter one. Similarly they will also favour adopting the cuter child.

Less attractive babies can suffer 'significant long-term adverse effects on their development', claim psychologists behind the review in the journal Trends in Cognitive Sciences.

Dr Morten Kringelbach, a neuroscientist at the University of Oxford, and his colleagues said physical abnormalities, such as a cleft lip, provided an example of the impact on babies.

They wrote: 'Having cleft lip changes the typical 'cute' infant facial configuration even though only a small proportion of the face is affected.

'This morphological change, in turn, is associated with adverse outcomes in child development, including cognitive problems.

'These problems can at least partly be attributed to early disruptions in mother–child interactions, specifically a lack of all-important maternal responsiveness.

'Nonparents report finding infants with cleft lip less 'cute' than typical infants.'

One study in the journal Public Library of Science One showed that men tended to spend less time looking at the faces of infants with cleft lips than women, but earlier studies have also suggested that women will exert more effort to remove pictures of 'ugly babies' than men will.

Experiments by Dr Kringelbach and his colleagues have also shown that when non-parent adults view the faces of infants with cleft-lips, the activity in the orbitofrontal cortex is significantly reduced.

Normally when looking at infant faces, adults' brains light up with activity in this area very rapidly.

Adults looking at pictures of cute babies show a rapid spike in activity in the medial orbitofrontal cortex of their brains that is not so pronounced when looking at the faces of adults (illustrated above). Similarly this effect is less pronounced in babies that are considered to be less attractive

Babies with large eyes, oversized heads, small chins, chubby cheeks and button noses (pictured) are usually regarded as being cute. These features seem to trigger a mechanism that is hardwired in the human brain

This can also extend to the sounds – such as laughter and babbling - and smells typically associated with 'cute' babies.

Writing in the journal, the authors explain: 'Infant cues spur us to action. Both men and women will expend extra effort to look longer at cute faces.

'Adults who see an infant face before a simple task have faster reaction times and sustain their engagement in the task.

'Therefore, cuteness is a fundamental mechanism that helps to elicit care giving.'

Babies with cute faces (shown on the left) tend to attract more attention from adults than less cute faces (right)

It is not clear whether the effects seen with babies suffering from cleft lips might extend to less severe perceptions of 'ugly' babies.

But, fortunately for those unlucky enough to be born with thick eyebrows, furrowed brows and potato-like noses, it appears the 'cute effect' seems to diminish with age.

Dr Kringelbach and his colleagues said: 'The power of cuteness to capture attention may diminish as a child develops.

'Both adults and children pay more attention to infants' faces than to older children's faces, suggesting that the power of cuteness in young children's faces fades as children mature.'