Hi Timon and welcome from me too
Do you know what colour eggs they hatched from and were these the only ones that hatched? If not, were all the other chicks the same colour white?
I'm not convinced they are leghorns as they have red ear lobes and leghorns should have white ears. Unfortunately I'm pretty sure at least 2 of them are cockerels.... the two on the right hand side.... as you can see their sickle feathers (curved tail feathers) sprouting. I can't comment on the other two because you can't see their tails but since all have very similar comb and wattle development, it would be reasonable to deduce that they are all males. (individual close up side shots of each bird would help identify gender)
You can also see some red leakage coming through in their feathers which might suggest that they are actually male red sex links although it would be unusual I think for them to be quite so uniformly white with so little red. I personally don't think they are meat birds, because at 14 weeks they would be twice that size and so overweight they would be unable to stand.... they get harvested at 8-10 weeks.
You may need to start being vigilant when your 5 yr old is with you, as once they hit adolescence, their temperament may well change and as someone who has been flogged by a rooster, I can tell you it is an intimidating and dangerous experience for an adult let alone a child.... so please do be careful. That said, not having any hens amongst them and having been brought up together may help to keep them more amicable, but please do just be aware that things can change from one day to the next once their hormones kick in, which will start to happen in the next few weeks.
I appreciate that you may well already be attached to these birds but if I'm right and they are all male, keeping 4 cockerels is going to be a problem, particularly if you also want to keep some hens for eggs and my advice would be to teach your family the realities of where meat comes from, with at least 3 of them and "invite them to dinner". I know that sounds callous, but I imagine this is part of educating children about where food comes from and even if you are vegetarian and eat eggs, it is unreasonable to ignore the plight of millions of male birds in the egg production industry that get culled as day old chicks.... I seem to be making a case for veganism here!!
I learned at a reasonably young age as my mother helped with poultry on a friend's farm and my sister and I would help pluck them at Christmastime. Looking back it is really surprising how we accepted that this was what happened and although I grew up to be incredibly soft hearted and even move worms off the path when I see them, I am now keeping and raising chickens for myself and the excess cockerels have to be dealt with. That early education at the farm has stood me in good stead and although I find killing incredibly difficult, I am able to do it because it is my responsibility. They have a far better life than any supermarket chicken and a quick death at the hand of someone who cares, rather than the mass slaughter that happens in chicken factories.
Oh Gosh! I seem to have stepped up onto a soap box..... how did that happen
Sorry, really didn't mean to lecture..... just wanting to outline the less pleasant and less talked about side of poultry keeping that unfortunately you may need to research.
Good luck whatever you decide, but do be careful with your child around adolescent roosters.
Best wishes
Barbara