Three kittens in my backyard

This morning I saw three kittens in my backyard, and I know there is a mother who frequently walks by, so I'm assuming its theirs. I'm not sure how old the kittens are, two of them play with eachother and walk around and aren't scared of humans whatsoever. They seem almost apathetic, could this be a sign of illness? They don't respond to most movements or touching. Another kitten has stayed as far as possible into the bush. One of the playful kittens seems to have something wrong with its eye. I don't know if something is stuck in there or if it's deformed or what. I would love to take one of them home, but I would not be able to take all three. Is it alright to take one away from it's mother and siblings if it is clearly able to walk away from their shelter? How do kittens react to family members? Would it be unethical to take it away from the rest of the family? I've put out water and kitty food but none of them touch them at all. They get close, look, then leave. Any help would be appreciated.

The ideal is to catch all of them and find them homes before they become feral but life is not always ideal. If you can care for one of them that is great. Maybe you can catch the others and maybe you can't. I had to learn this recently. You can do your best and some will slip through your fingers.
I have 2 from a litter of four. I could never catch the other two.
Do the best you can and what you can. It is better than doing nothing.
Good luck.