As @zenvelo has mentioned, there have been research studies done with children. As a matter of fact they’ve even used infants just a few months old so it’s obvious they haven’t yet the language facility or maturity to pick up on the dictates of society.
And it is independent of whichever culture they’re surrounded by.
So, here is the general rule of thumb. People (including infants) are attracted to faces which are symmetrical. This is why things such as buck teeth, small beady eyes, etc. are considered less attractive (or beautiful).
As a matter of fact there is a mathematical relationship known as the “Golden Ratio” or “Golden Mean” which is a series of numbers which represent this universal standard of beauty and symmetry in both objects and people. The closer a persons face or an object comes to representing this pattern the more attractive it is perceived to be.
It’s also known as the Fibonacci Sequence, named for the mathemetivian who first observed it.
I dont remember the specific numbers offhand but if you do a search on Fibonacci, it will give you the sequence of numbers as well as numerous examples where this pattern can be found. It’s really a fascinating read.
This was first observed in nature in things like flower petal disbursement and the shell of a Nautilus, to name just a few.
But it’s also used in fields of expertise as widely diverse as Architecture as well as reconstructive surgery. For a surgeon altering a face, there is a template of lines fitting over a face connecting all types of measurements like eye width, nose in relation to mouth and eyes and all other connecting points which depicts how the Fibonnacci sequence would bring all these points into the most balanced and symmetrical form.
They’ve also used this template and placed it over the faces of various celebrities (both those widely considered attractive and beautiful as well as those not so) and you can clearly see that the closer they fit the template of the Golden Ratio, the more attractive they’re considered to be.
This is why someone with the facial structure of Brad Pitt or Julia Roberts is considered more attractive than someone like Lyle Lovett or Sandra Bernhard. Symmetry.
(Obviously Lyle had other qualities of mind, personality, or creativity which Julia found attractive enough to marry but it wasn’t for his facial features.)
So, bottom line, speaking on a PURELY PHYSICAL basis, the more symmetrical and balanced the facial features, the more they are considered attractive by both infants and the majority of society as a whole.
This is also found in many works of great artists down through the ages. The Fibonacci sequence is all over the place with remarkable consistency.
As a matter of fact some have suggested that this is evidence of a Creator. Interesting.