The eyes of a mother?

So I have these 2 boys. 6 & almost 8.

I look at them and they look nothing alike. I wonder how the same man and I could have produced 2 so different looking boys. But I know they're both ours, they never left our sight after birth.

The oldest, Oceanus, is olive skinned with hazel eyes - they are mainly green but can be blue or gray depending on mood or clothes. He has brown hair, but it leans on the blonde side. Plus, he's lost baby teeth and now has super big adult teeth.

The youngest, Hyperion, is possibly the whitest kid I have ever seen who is not an albino. He has freckles everywhere the sun touches. And I do mean everywhere - even on his eyelids. I have no doubt that if his hair ever got long enough to part, he'd have freckles on his scalp. He has brown hair that leans to the very dark side. And blue eyes - this kid's eyes are such a blue. He hasn't lost any teeth yet, we're waiting for him to lose the front tooth, it's that or have the dentist pull it.

Recently, Hyperion has had a growth spurt. He is now within about 2 inches of being as tall as his brother and is possibly the same weight. They wear the same size clothes.

We've been asked no less than 5 times in the last month if they are twins. And everyone says how much they look alike. I? Can't see it at all. And it's not just clueless adults, it's other kids. Other kids see them and ask if they're twins.

Is this what they mean by "mother's eyes"? Is it that they really do look just alike and I don't see it because I know them so well? Or maybe it's me. After all, I look at pics of 2 identical twins I went to HS with and I know instantly which is which. Shelly is so obviously not Kelly, how could anyone not see it?