Brothers From the Same Mother?

I've been trying to figure out how to write this post in a way that years from now my children won't read it and be mad at me. But, it's something I think about a lot: how different my 2 oldest boys are. Even when I was pregnant with them, I could tell they were opposites. Even while in the womb, I felt like this almost psychic connection with my oldest, like I just know what he's thinking (probably because we are WAY too much alike!), while, with my middle son, I have no idea what makes him tick and felt no "I can read your mind" connection while I was pregnant (that never worried me by the way, I still feel very connected to him, just in a different way from his brother). I had a very tough delivery with my oldest and it did not get easier from there. He had colic and was a difficult baby for the first few months. His saving grace was that he slept through the night at an early age and has always been a good night sleeper (though nowadays the trick is getting him to GO to sleep, but once he is out, he's out). J's labor was sooo much easier than his brother's and the nurse summed up J's personality before he even came out by saying "he's one happy little guy!" J, as a baby, was what I had dreamed babies to be like before I had my first one: content, fun to play with, just able to hang out with the family and go with the flow. He was a good napper but a horrible night sleeper and he had acid reflux (which thankfully went away at 6 months). As the boys have grown older, these differences have only grown and I seriously wonder how these two boys came from the same parents! Everything that was such a struggle with my oldest has been so much easier with his brother (for instance, getting my oldest to say please and thank you--you'd think I was demanding the moon and then all the sudden in the last week J has started to say them without me even asking him to) and everything that came easily to my oldest has been harder for J (my oldest talked very early and very well while J at 2 and a half is getting speech therapy). Oh, they do have their things in common like both are momma's boys and have had their stages of major separation anxiety, but it makes me wonder if my 3rd boy will be somewhere in the middle of his two polar opposite brothers. So far, I see a little of both boys in my youngest. But what are the siblings like in your house? Are there opposites in every family?