I come from a large and spread out family - I'm first of 8. (All of the same mum and dad.) My youngest brother is 19 years younger than me. Right now, he is 8. I got married and moved out when he was not quite 2, so I have to say that the relationship I have with him and my next youngest sister (17yrs younger) is different than what I have with the siblings closest to me (my sister closest to me is my best friend) but I love them just as much! I mean, how can you really compare the relationship you have with a 25 year old, compared with what you have with a 10 and 8 year old? But as they grow older, we talk more, and they love being "aunt" and "uncle" to mine and my sister's kids, and we all get along great. I don't know them in the same way, right now, that I know some of my other siblings, but as I said, as they get older, the age gap becomes less noticeable, and I love them just the same anyways.
When the youngest two were babies - I loved it! I was still at home then, and it was like having my own baby, without the waking at night or discipline issues. We all spoiled them rotten. (The last two came after a six year gap.) I think it gave my mom a break a little bit too, since we were old enough to help with housework, and caring for the baby. We loved them to bits.
Sorry if that's a bit of a confusing answer, but it's the best I can explain it!