Girls behave more grown than boys?

So my husband, my brother and I were all watching YouTube when we came across a video titled: Say what with two little girls named Dannah and Dani and then it lead over to another video called cuteness alert. It was about the same little girls made an appearance on a television show called The Real. After watching both videos I had nothing to say. I don't have a daughter. My husband and I have a son. My brother starts talking and he was saying how if his daughters acted like that they'd get some type of punishment and some privileges taken away his daughters are roughly around the same age as the two girls (slightly older). He goes on to tell my husband how lucky he is for having only a son because we won't have to worry about our son trying to act all grown up and sassy. My husband laughed and said he wouldn't mind having a daughter... it's all about how a kid is parenting basically determines how they behave for the most part. My brother then said that it's a well known fact that girls are more likely to try and act grown up than boys. He said boys don't behave like that and therefore are also less likely to lie about their age. I was quiet the majority of the time but I had to say something about that. I've met plenty of boys while I was growing up that lied about their age or snuck into clubs or acted like a grown up when they weren't. Do you believe that girls are the only ones who act all grown up? Do you feel like little girls who act this way are too grown and shouldn't be allowed to behave this way or do you think they are just having fun?