Is it normal for two siblings to have antisocial personality disorder?

I've shown signs of antisocial personality disorder since a young age. I've never tortured animals or committed any serious crimes as commonly associated with being a "sociopath". That being said, I am not stupid. Such actions can have consequences that scarcely bear thinking about. I've always had a pretty good handle on things.

Lately especially, I've been noticing that my younger brother (aged 13 nearing 14) has started showing a few trademark signs of antisocial personality disorder.

He has no respect for me, my mother, or anyone for that matter (I know that people often just say this for the effect or as an exaggeration, but I mean that he literally does not respect people.)

For example, we attended the funeral of my great uncle (our grandmother's brother, we are very close to our grandparents) the other day. Obviously, there are ways that you have to act at a funeral, even if you aren't personally grieving. Look sad, be repectful, do what everyone else seems to be doing. In a room full of grieving people, he simply could not behave himself. Instead, he was constantly trying to wind me up, he was looking at things he wanted on his phone and showing them off to whoever would look. It was as if he had no idea that the people around him were in pain.

He's constantly getting in trouble at school, and he's so aggressive towards near enough everyone. He explodes like a bottle of pop. Like I said, I've always had a good handle on things. If someone does something to upset me, I tend to get back at them in my own way - inconspicuously. The other times I explode too.

He doesn't seem to have much in the way of a conscience. He steals money (albeit only small amounts) and will only admit it when he is put under pressure and it is made blindingly obvious that the person he stole from knows he stole from them. Even then, he will not apologise without being nudged into it.
I learned at a very young age that apologising usually gets you back on someone's good side, he doesn't seem to notice these things.

This story is already too long and I really can't be bothered to go into our life stories and I don't have the time anyway.

I want to know if it is common - or normal - for two people with antisocial personality disorder to be siblings? I thought it was much more rare, and it's unclear whether the condition is genetic or not.
It seems to me that we are very similar, and the only difference is that I have more self control and dicipline.