I have 3 kids. My wife had two already when we met. I am helping raise them as they primarily live with us. They are 9 years older than our youngest we had together. This is problematic because they are so used to being the only kids, and they tend to complain about their treatment versus their younger sister. I understand that the age gap isn't ideal. Optimal is 3 years apart. But that couldn't be helped so oh well. Anyway, in a very different parent to them than I am to my flesh and blood daughter, and they resent her for it. Don't get me wrong, they love their little sister. But both of them, sooner or later, start to get mean to her out of resentment. She's only 3, and we have to remind them it's not fair to her. My oldest daughter is constantly hovering over her and getting in her personal space to the point she screams go away whenever she enters the room. We've been telling her repeatedly over the past 3 years to back off or her little sister will grow to dislike her. She hasn't listened. In fact, she blocks us out when she is busy harassing her little sister. Meanwhile her big brother is her favorite sibling, which drives her crazy. But he doesn't harass her the way her older sister does, and she doesn't understand that either. I think the biggest problem with them is their inability to understand what's wrong with their behavior. They just can't see someone else's perspective. It leads to arguments and hurt feelings, and more resentment. After all, before baby sister arrived, these things didn't happen. It's really taken a toll on us. Now onto my step son, who is the constant pest to everybody but his baby sister. He's a very thoughtless child, which is extremely frustrating, considering this wasn't always the case. He says hurtful things to his mother and sisters and doesn't understand why they get mad at him. He's also deliberately mean to his twin sister and his mother. He's got the same problem of a complete inability to see someone else's perspective, and he's extremely selfish. Everything is unfair if it doesn't benefit him, and he'll annoy the hell out of you for the fun of it. His mom calls him an asshole at least once a week because of the way he treats her and his twin sister. He's also extremely lazy and refuses to contribute around the house except when he decides he wants to, once or twice a year. All this being said, I haven't been a great father to them. I've been immature and have reacted poorly to their bad behavior, and they blame their little sister for it. I was much nicer to my oldest daughter when my little one wasn't here, mostly because I keep needing to yell at her when she refuses to stop making her little sister upset. Instead of seeing her own culpability, it's just me being mean and her little sister being my favorite. Meanwhile I'm being very immature and acting like a child myself, which doesn't help. I'm trying to stop, and I'll have a good streak going for a while, but sooner or later, I'll be mean to them. I take most of it out on my step son. He is constantly trying to argue and get his way by refusing to accept anyone's interpretation but his own, and he's constantly getting in trouble with his mouth running when he needs to stop. But if I don't ignore him, which we all do, really, I end up screaming at him or threatening him with bodily harm in extreme cases. I really don't want to be that person. These two just bring out the worst in me sometimes. The worst part for me is that I'd be much nicer if they were my flesh and blood. Other people's poorly behaved children just always get to me. I do see them as my kids and I do love them. I just wish it was more obvious. Sometimes they don't think I love them. But how do I stop overreacting and making things worse? I'm certainly not fully at fault, but I'm the adult and need to act the part. Neither of my parents yelled at me as often as I've yelled at these two, and that was 18 years worth of parenting versus me only being their dad for 6 years of their 12. I really need to fix it before they move out and avoid being around me when they don't have to be, while also not reinforcing their negative behaviors. sigh