Charlize Theron says her children can be ''assholes''.

The 42-year-old actress adopted Jackson, six, (who she calls Jacks) in 2012 and August, (Auggie) two, in 2015, and while she adores her children, she admitted they are not always little angels.

She told US Elle magazine: ''A child in my twenties was the scariest idea I could think of. When I got to my thirties, I was so ready. But there's a moment where you're like, Oh God, I hope once I have my kids, I'm still going to want to be a parent this much. I have bad days. I make mistakes. Going through the tantrum stages when they're such little assholes. And they choose the worst moments. It's a lot for one person. But after six years of having my two nuggets, there's not a day when I wish I hadn't done this.''

However, Charlize revealed that the adoption process was one of the hardest things she ever went through.

She said: ''I struggled mentally through the adoption process. Some of the lowest points in my life were dealing with the first time I filed; it really took an emotional toll. There were many situations that didn't work out, and you'd get attached and have all your hopes up and then just get crushed. So I was in a different mind space. I had different needs.''

While the adoption process was tough, Charlize admitted she has found criticism from ''judgy moms'' a challenge but says she tries to ignore it.

She said: ''I've had a lot of moms come up to me and tell me I'm screwing everything up. Both my kids grew up on formula, and I remember a mom saying to me, 'You should really buy breast milk.' And I was like, What?! That's a line you just don't cross.

''My oldest just started big school. She's not even there a full year. So I've not gotten into the whole [judgy moms at] school thing yet. The good thing about me is, I've never given a sh*t about what people think. That's the only quality I have that has probably helped me in being a mother.''

And although the star is not in a relationship, she relies heavily on her mother Gerda for help in raising her children.

She explained: ''I knew that I would have to have my mom help me if I was going to do this as a single parent. To not acknowledge her in coparenting my children would be a lie. She has jokingly said, 'Being a grandparent is what I was born to do.' I was like, 'Yo, bitch! What about me? Was it not to raise me? I'm your kid!' But I'm so lucky to have that. I would feel pretty alone if I didn't have a partner in crime in all of this.''