I find it so odd that two people can be raised in the exact same environment and turn out so differently/ have opposing characteristics. What is something you and your sibling are opposite about? My parents and I are very punctual and reliable. If we say we will be somewhere at certain time- we are there and we are there early.
My brother is a year older than me and he has become a total flake. He either shows up 2 hours late or not at all, without even a call. My grandma just called me devastated because he was supposed to bring his new baby to visit her on Sunday. She bought all this food and he was a no show no call. And he doesn't have valid reasons or excuses because I see on his facebook that he's just out playing basketball with his buddies or something like that. He is selfish with his time and never shows up to obligations (like family Christmas) and I have no idea where he got this from since the rest of us are not like that!