Sallow, pale, raccoon-eyed babies?

[Linguaphile]

My 11mo twins have looked like this for a few months nowjust generally unhealthy complexionsand I'm not sure why. It's been like this for months--sallowish, pale, see-through skin and slight dark circles under their eyes. I feed them a balanced diet of fruit, veg, dairy, protein and carbs, and they still drink between 500 and 750 ml of formula/day (which should theoretically contain the vitamins they need to be getting). They sleep 7-7 and get regular 2.5 hours of daytime naps. We go outside a lot, so it's not like I keep them indoors.

Is it just the way they look, or am I missing something health-wise???

Do they have any allergies? I remember doing a lot of reading about allergies as I thought DD might have them, as she always had eye bags. Turned out in her case it came from her tear ducts having not formed properly, which corrected themselves around 1yo. But I do remember that circles under the eyes are considered an allergic shiner.

Hmmm I wonder what sort of allergy would cause that?

Here's a photo of one them, just to show you what I mean. It's not terrible, but not exactly screaming 'healthy' either...