I don't mean to come across as "judgy" here, but you should have got your boys out of the mess that is your "home" with SD15 antics a long time ago. Those boys are now suffering the consequences. The ages of birth to age 5 are the most formative years for children. 85 percent of a child's intellect, personality and social skills are developed by that age. Your boys have spent those years living in a nightmare. A nightmare that even YOU have a hard time dealing with can you imagine what it must be like for them?

Well, a couple of things.... one, part of it is just normal for boys that age. There's nothing wrong with them. Of course, that being said, you DO still have to teach them better. (So, while the behavior is pretty normal for the age, you still have some work to do. Which is a normal part of being a parent!)

Now, as to the aggression itself, there are a few things to get in order. The first is the physical stuff. How's their sleep? Going to bed early enough? Waking up rested? How about what they eat? Some people find that dyes in food (especially red dye for some reason) can enhance aggressive tendencies. Sometimes sugar is a culprit. Keep a journal of what they eat and their behavior and see if there's any pattern. And also, I agree with a PP - stop spanking. That definitely increases aggression.

I like your consequences for poor behavior (loss of games), but how about a positive reward for GOOD behavior? Often using the combination works better than using one alone. A sticker chart can be great, and you can even give it to the day care! Use a regular piece of paper, and have 5 columns and 2 rows. One column for each day of the week, and one row for "morning" and one for "afternoon" (at that age, the whole day is just too overwhelming - break it into chunks). If they have a good morning and keep their hands to themselves, they get a sticker! If, at the end of the week, they have so many stickers (start with something they can do, maybe 5) then they can pick a movie to watch, or you can have a "pirate treasure box" with small toys they can choose, something like that.

OH! And also, the 5 year old especially can start to learn empathy! Draw an empty box on a piece of paper. Draw 2 arrows going out from the box, one going to a smiley face and one to a sad face. Then you can talk to the 5 year old about his b behavior choices and how it made the other child feel. "You grabbed a toy from him. Do you think that made him happy or sad? Can you point to the right picture?" (This is actually from an autism therapist, but she said it can often work with 5 and 6 year old neurotypical kids as well!)