My nephew

Me and my fiance look after my nephew because my sister get really sick so his kinda like ours too but he keeps wettin the bed he never used to do you think his just being lazy or should I look deeper ?

depends how old he is.
he probably has an issue you should talk to him about.

I'm guessing it's because his world changed when you and your fiance started looking after him. He probably misses his mum. This is something very normal for him to go through. Try not to get mad at him...it's not like he's trying to do it.

You could wake him up at night before you go to bed, to take him to the bathroom. That should help him to get through the night.

Good luck