Sometimes these things even out. I am two years older than my sister but it always looked like more, because growing up I was in the 75% for height and she was in the 25%. I stopped growing at 14; she kept growing until 17, and now as adults we are only an inch apart. I am still taller ( ), but it's not nearly as noticeable as when we were kids and I towered over her.

However, I think it's a bit different for boys, and certainly a bit of a sting for the younger boy to be taller. My cousin's kids are like this. The middle boy is only an inch or so taller than his younger brother who is 3 years younger. And middle boy is 15 so he's already partway through puberty. He's going to be a short man, like 5'3" or 5'4", and there's nothing to be done. I think he's a bit more sanguine about it now that as a teenager he looks more mature, and is starting to get privileges like driving, but it bothered him for a long time. For years people mistook him and his little brother for twins, and he did not like it.